A002386 -id:A002386 - cp's OEIS frontend

A005669 Indices of primes where largest gap occurs.

1, 2, 4, 9, 24, 30, 99, 154, 189, 217, 1183, 1831, 2225, 3385, 14357, 30802, 31545, 40933, 103520, 104071, 149689, 325852, 1094421, 1319945, 2850174, 6957876, 10539432, 10655462, 20684332, 23163298, 64955634, 72507380, 112228683, 182837804, 203615628, 486570087

Offset: 1

N. J. A. Sloane

nonn

Conjecture: log a(n) ~ n/2. That is, record prime gaps occur about twice as often as records in an i.i.d. random sequence of comparable length (see arXiv:1709.05508 for a heuristic explanation). - Alexei Kourbatov, Mar 28 2018

H. Riesel, Prime numbers and computer methods for factorization, Progress in Mathematics, Vol. 57, Birkhäuser, Boston, 1985, Chap. 4, see pp. 381-384.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

John W. Nicholson, Table of n, a(n) for n = 1..82 (first 77 terms from Charles R Greathouse IV)
Jens Kruse Andersen, The Top-20 Prime Gaps.
Jens Kruse Andersen, New record prime gap.
Jens Kruse Andersen, Maximal gaps.
R. K. Guy, Letter to N. J. A. Sloane, 1987.
Alexei Kourbatov, Tables of record gaps between prime constellations, arXiv preprint arXiv:1309.4053 [math.NT], 2013.
Alexei Kourbatov, On the nth record gap between primes in an arithmetic progression, arXiv:1709.05508 [math.NT], 2017; Int. Math. Forum, 13 (2018), 65-78.
Alexei Kourbatov and Marek Wolf, Predicting maximal gaps in sets of primes, arXiv preprint arXiv:1901.03785 [math.NT], 2019.
Thomas R. Nicely, First occurrence prime gaps. [For local copy see A000101]
Matt Visser, Verifying the Firoozbakht, Nicholson, and Farhadian conjectures up to the 81st maximal prime gap, arXiv:1904.00499 [math.NT], 2019.
Robert G. Wilson v, Notes (no date).
J. Young and A. Potler, First occurrence prime gaps, Math. Comp., 52 (1989), 221-224.
Index entries for primes, gaps between

Cf. A000101, A002386, A005250.

f[n_] := Block[{d, i, m = 0}, Reap@ For[i = 1, i <= n, i++, d = Prime[i + 1] - Prime@ i; If[d > m, m = d; Sow@ i, False]] // Flatten // Rest]; f@ 1000000 (* Michael De Vlieger, Mar 24 2015 *)

a(n) = A000720(A002386(n)).

a(n) = A107578(n) - 1. - Jens Kruse Andersen, Oct 19 2010

A111870 Prime p with prime gap q - p of n-th record merit, where q is smallest prime larger than p and the merit of a prime gap is (q-p)/log(p).

Original entry on oeis.org

2, 3, 7, 113, 1129, 1327, 19609, 31397, 155921, 360653, 370261, 1357201, 2010733, 17051707, 20831323, 191912783, 436273009, 2300942549, 3842610773, 4302407359, 10726904659, 25056082087, 304599508537, 461690510011, 1346294310749, 1408695493609, 1968188556461, 2614941710599, 13829048559701, 19581334192423, 218209405436543, 1693182318746371

Offset: 1

N. J. A. Sloane, based on correspondence with Ed Pegg Jr, Nov 23 2005

nonn

As I understand it, the sequence refers to "Smallest prime p whose following gap has bigger merit than the other primes smaller than p." If that is the case, then it has an error. The sequence starts: 2, 3, 7, 113, 1129, 1327, 19609, 31397, 155921, 360653, 370261, 1357201, 4652353, 2010733, ... but you can see that 4652353 > 2010733, so in any case it should be listed after, not before it. But above that, its merit is 10.03 < 10.20, the merit of 2010733, so it is not in a mistaken position: it shouldn't appear in the sequence. - Jose Brox, Dec 31 2005
The logarithmic (base 10) graph seems to be linearly asymptotic to n with slope ~ 1/log(10) which would imply that: log(prime with n-th record merit) ~ n as n goes to infinity. - N. J. A. Sloane, Aug 27 2010
The sequence b(n) = (prime(n+1)/prime(n))^n is increasing for terms prime(n) of this sequence. - Thomas Ordowski, May 04 2012
The smallest prime(n) such that (prime(n+1)/prime(n))^n is increasing: 2, 3, 7, 23, 113, 1129, 1327, ... (A205827). - Thomas Ordowski, May 04 2012
(prime(n+1)/prime(n))^n > 1 + merit(n) for n > 2, where merit(n) = (prime(n+1)-prime(n))/log(prime(n)). - Thomas Ordowski, May 14 2012
Merit(1) + merit(2) + ... + merit(n) =: S(n) ~ n, where merit(n) is as above. - Thomas Ordowski, Aug 03 2012
For the index of a(n), see the comment at A214935. - John W. Nicholson, Nov 21 2013

			The first few entries correspond to the following gaps. The table gives n, p, gap = q-p and the merit of the gap.
   1,       2,   1, 1.4427
   2,       3,   2, 1.82048
   3,       7,   4, 2.05559
   4,     113,  14, 2.96147
   5,    1129,  22, 3.12985
   6,    1327,  34, 4.72835
   7,   19609,  52, 5.26116
   8,   31397,  72, 6.95352
   9,  155921,  86, 7.19238
  10,  360653,  96, 7.50254
  11,  370261, 112, 8.73501
  12, 1357201, 132, 9.34782

Ed Pegg, Jr., Posting to Seq Fan mailing list, Nov 23 2005

Hugo Pfoertner, Table of n, a(n) for n = 1..39, extracted from pzktupel link.
Jens Kruse Andersen, The Top-20 Prime Gaps
Jens Kruse Andersen, Maximal gaps
Jens Kruse Andersen, Record prime gaps, current version maintained by Norman Luhn.
Thomas R. Nicely, First occurrence prime gaps [For local copy see A000101]
Eric Weisstein's World of Mathematics, Prime Gaps

For the gaps, see A111871.

Cf. A002386, A111943, A214935, A277552.

With[{s = Map[(#2 - #1)/Log[#1] & @@ # &, Partition[Prime@ Range[10^6], 2, 1]]}, Map[Prime@ FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]]] (* Michael De Vlieger, Jul 19 2018 *)

a(n) = A277552(n) - A111871(n). - Bobby Jacobs, Nov 13 2016

Corrected by Jose Brox, Dec 31 2005
Corrected and edited by Daniel Forgues, Oct 23 2009
Further edited by Daniel Forgues, Nov 01 2009, Nov 13 2009, Nov 24 2009

A113274 Record gaps between twin primes.

Original entry on oeis.org

2, 6, 12, 18, 30, 36, 72, 150, 168, 210, 282, 372, 498, 630, 924, 930, 1008, 1452, 1512, 1530, 1722, 1902, 2190, 2256, 2832, 2868, 3012, 3102, 3180, 3480, 3804, 4770, 5292, 6030, 6282, 6474, 6552, 6648, 7050, 7980, 8040, 8994, 9312, 9318, 10200, 10338, 10668

Offset: 1

Bernardo Boncompagni, Oct 21 2005

nonn

a(n) mod 6 = 0 for each n>1.

			The first twin primes are 3,5 and 5,7 so a(0)=5-3=2. The following pair is 11,13 so a(1)=11-5=6. The following pair is 17,19 so 6 remains the record and no terms are added.

Martin Raab, Table of n, a(n) for n = 1..82 (terms up to a(72) from Alexei Kourbatov, a(73)-a(75) from Tomás Oliveira e Silva)
Richard Fischer, Maximale Lücken (Intervallen) von Primzahlenzwillingen
G. H. Hardy and J. E. Littlewood, Some problems of 'partitio numerorum'; III: on the expression of a number as a sum of primes, Acta Mathematica, Vol. 44, pp. 1-70, 1922.
Alexei Kourbatov, Maximal gaps between prime k-tuples
Alexei Kourbatov, Maximal gaps between prime k-tuples: a statistical approach, arXiv preprint arXiv:1301.2242 [math.NT], 2013; and J. Int. Seq. 16 (2013) #13.5.2
Alexei Kourbatov, Tables of record gaps between prime constellations, arXiv preprint arXiv:1309.4053[math.NT], 2013.
Alexei Kourbatov, The distribution of maximal prime gaps in Cramer's probabilistic model of primes, arXiv preprint arXiv:1401.6959 [math.NT], 2014.
Alexei Kourbatov and Marek Wolf, Predicting maximal gaps in sets of primes, arXiv preprint arXiv:1901.03785 [math.NT], 2019.
Mersenneforum, Gaps between prime pairs (Twin Primes).
Tomás Oliveira e Silva, Gaps between twin primes
Luis Rodriguez and Carlos Rivera, Conjecture 66. Gaps between consecutive twin pairs, The Prime Puzzles and Problems Connection.
Eric Weisstein's World of Mathematics, k-Tuple Conjecture
Eric Weisstein's World of Mathematics, Twin Prime Constant

The smallest primes originating the sequence are given in A113275. Cf. A008407, A005250, A002386.

NextLowerTwinPrim[n_] := Block[{k = n + 6}, While[ !PrimeQ[k] || !PrimeQ[k + 2], k+=6]; k]; p = 5; r = 2; t = {2}; Do[ q = NextLowerTwinPrim[p]; If[q > r + p, AppendTo[t, q - p]; Print[{p, q - p}]; r = q - p]; p = q, {n, 10^9}]; t (* Robert G. Wilson v, Oct 22 2005 *)
DeleteDuplicates[Differences[Select[Partition[Prime[Range[10^7]],2,1],#[[2]]-#[[1]] == 2&][[All,2]]],GreaterEqual] (* The program generates the first 27 terms of the sequence. *) (* Harvey P. Dale, Dec 31 2022 *)

a(n) = A036063(n) + 2.
a(n) = A036062(n) - A113275(n).
From Alexei Kourbatov, Dec 29 2011: (Start)
(1) Upper bound: gaps between twin primes are smaller than 0.76*(log p)^3, where p is the prime at the end of the gap.
(2) Estimate for the actual size of the maximal gap that ends at p: maximal gap = a(log(p/a)-1.2), where a = 0.76*(log p)^2 is the average gap between twin primes near p, as predicted by the Hardy-Littlewood k-tuple conjecture.
Formulas (1) and (2) are asymptotically equal as p tends to infinity. However, (1) yields values greater than all known gaps, while (2) yields "good guesses" that may be either above or below the actual size of known maximal gaps.
Both formulas (1) and (2) are derived from the Hardy-Littlewood k-tuple conjecture via probability-based heuristics relating the expected maximal gap size to the average gap. Neither of the formulas has a rigorous proof (the k-tuple conjecture itself has no formal proof either). In both formulas, the constant ~0.76 is reciprocal to the twin prime constant 1.32032...
(End)

More terms from Robert G. Wilson v, Oct 22 2005
Corrected terms based on A036063, cross-checked with independent computations by Carlos Rivera and Richard Fischer (linked).
Terms up to a(72) are given in Kourbatov (2013), terms up to a(75) in Oliveira e Silva website.

A014320 The next new gap between successive primes.

Original entry on oeis.org

1, 2, 4, 6, 8, 14, 10, 12, 18, 20, 22, 34, 24, 16, 26, 28, 30, 32, 36, 44, 42, 40, 52, 48, 38, 72, 50, 62, 54, 60, 58, 46, 56, 64, 68, 86, 66, 70, 78, 76, 82, 96, 112, 100, 74, 90, 84, 114, 80, 88, 98, 92, 106, 94, 118, 132, 104, 102, 110, 126, 120, 148, 108, 122, 138

Offset: 1

Hynek Mlcousek (hynek(AT)dior.ics.muni.cz)

nonn

Prime differences A001223 in natural order with duplicates removed. - Reinhard Zumkeller, Apr 03 2015

Conjecture: a(n) = O(n). See arXiv:2002.02115 for discussion. - Alexei Kourbatov, Jun 04 2020

			The first two primes are 2 and 3, and the first prime gap is 3 - 2 = 1; so a(1) = 1. The next prime is 5, and the next gap is 5 - 3 = 2; this gap size has not occurred before, so a(2) = 2. The next prime is 7, and the next gap is 7 - 5 = 2; the gap size 2 has already occurred before, so nothing is added to the sequence.

Brian Kehrig, Table of n, a(n) for n = 1..754 (terms 1..120 from Reinhard Zumkeller, 121..745 from Alexei Kourbatov).
Alexei Kourbatov and Marek Wolf, On the first occurrences of gaps between primes in a residue class, arXiv preprint arXiv:2002.02115 [math.NT], 2020.

Cf. A000101, A001223, A002386, A005250, A330853, A334543, A335366, A335367.

import Data.List (nub)
a014320 n = a014320_list !! (n-1)
a014320_list = nub $ a001223_list
-- Reinhard Zumkeller, Apr 03 2015

max = 300000; allGaps = Transpose[ {gaps = Differences[ Prime[ Range[max]]], Range[ Length[gaps]]}]; equalGaps = Split[ Sort[ allGaps, #1[[1]] < #2[[1]] & ], #1[[1]] == #2[[1]] & ]; firstGaps = ((Sort[#1, #1[[1]] < #2[[1]] & ] & ) /@ equalGaps)[[All, 1]]; Sort[ firstGaps, #1[[2]] < #2[[2]] & ][[All, 1]] (* Jean-François Alcover, Oct 21 2011 *)
DeleteDuplicates[Differences[Prime[Range[10000]]]] (* Alonso del Arte, Jun 05 2020 *)

my(isFirstOcc=vector(9999, j, 1), s=2); forprime(p=3, 1e8, my(g=p-s); if(isFirstOcc[g], print1(g, ", "); isFirstOcc[g]=0); s=p) \\ Alexei Kourbatov, Jun 03 2020

val prime: LazyList[Int] = 2 #:: LazyList.from(3).filter(i => prime.takeWhile {
   j => j * j <= i
}.forall {
   k => i % k != 0
})
val primes = prime.take(1000).toList
primes.zip(primes.tail).map(p => p.2 - p._1).distinct // _Alonso del Arte, Jun 04 2020

a(n) = A335367(n) - A335366(n). - Alexei Kourbatov, Jun 04 2020

a(n) = 2*A014321(n-1) for n >= 2. - Robert Israel, May 27 2024

More terms from Sascha Kurz, Mar 24 2002

A111871 Prime gaps q-p with n-th record merit referred to in A111870.

Original entry on oeis.org

1, 2, 4, 14, 22, 34, 52, 72, 86, 96, 112, 132, 148, 180, 210, 248, 282, 320, 336, 354, 382, 456, 514, 532, 582, 588, 602, 652, 716, 766, 906, 1132, 1328, 1356, 1370, 1442, 1476, 1572

Offset: 1

N. J. A. Sloane, based on correspondence with Ed Pegg Jr, Nov 23 2005

The prime gaps q-p (corresponding to a(n)=p in A111870) have increasing record merit (q-p)/log(p). However, the prime gaps themselves are almost always monotonically increasing (with very high probability), but not always! And we do have an exception in the list above: a(14)=148 < a(13)=154! (But see next comment!)

Because the erroneous A111870(13) = 4652353 term was removed, a(13) = 154 was removed. This sequence is therefore monotonically increasing. - John W. Nicholson, Nov 18 2013

			A111870(4) = 113 and the next larger prime is 127, so 127 - A111870(4) = a(4) = 14.

Ed Pegg, Jr., Posting to Seq Fan mailing list, Nov 23, 2005

Jens Kruse Andersen, Norman Luhn, Record prime gaps.

For the primes p corresponding to the prime gaps q-p with n-th record merit, see A111870.

Cf. A002386, A277552.

a(n) = A277552(n) - A111870(n). - Bobby Jacobs, Nov 13 2016

Corrected and edited by Daniel Forgues, Nov 11 2009 and Nov 20 2009
Because the erroneous A111870(13) = 4652353 term was removed, a(13) = 154 was removed by John W. Nicholson, Nov 18 2013
a(33)-a(35) inserted by Bobby Jacobs, Nov 08 2016
a(37) added by Bobby Jacobs, Nov 09 2016
a(38) added by Rodolfo Ruiz-Huidobro, May 14 2024

A001632 Smallest prime p such that there is a gap of 2n between p and previous prime.

Original entry on oeis.org

5, 11, 29, 97, 149, 211, 127, 1847, 541, 907, 1151, 1693, 2503, 2999, 4327, 5623, 1361, 9587, 30631, 19373, 16183, 15727, 81509, 28277, 31957, 19661, 35671, 82129, 44351, 43391, 34123, 89753, 162209, 134581, 173429, 31469, 404671, 212777

Offset: 1

N. J. A. Sloane

Smallest prime preceded by 2n-1 successive composites. - Lekraj Beedassy, Apr 23 2010

			The first time a gap of 4 occurs between primes is between 7 and 11, so A000230(2)=7 and A001632(2)=11.

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 97, p. 34, Ellipses, Paris 2008.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

T. D. Noe, Table of n, a(n) for n = 1..595 (from Nicely)
L. J. Lander and T. R. Parkin, On the first appearance of prime differences, Math. Comp., 21 (1967), 483-488.
Thomas R. Nicely, First occurrence prime gaps [For local copy see A000101]
Index entries for primes, gaps between

Cf. A000230, A002386.

With[{pr=Partition[Prime[Range[35000]],2,1]},Transpose[ Flatten[ Table[ Select[pr,#[[2]]-#[[1]]==2n&,1],{n,40}],1]][[2]]] (* Harvey P. Dale, Apr 20 2012 *)

LIMIT=10^9; a=[]; i=2; o=2; g=0; forprime(p=3,LIMIT, bittest(g,-o+o=p) && next; a=concat(a,[[p,p-precprime(p-1)]]); g+=1<=i && a[i][2]<2*i, print1(a[i][1]",");i++)) \\ a[1] = [3, 1] is not printed, cf. A000230(0). Limit 10^7 yields a(1),...,a(70) in 0.3 sec @ 2.5 GHz. \\ M. F. Hasler, Jan 13 2011, updated Jan 26 2015.

a(n) = 2n + A000230(n) = nextprime(A000230(n)).

a(n) = A000040(A038664(n)+1). - M. F. Hasler, Jan 26 2015

More terms from Larry Reeves (larryr(AT)acm.org), Nov 28 2000 and from Labos Elemer, Nov 29 2000

Terms a(1)-a(146) checked with the PARI program by M. F. Hasler, Jan 13 2011, Jan 26 2015

A141042 Product of n and the n-th gap between primes: a(n) = n*A001223(n).

Original entry on oeis.org

1, 4, 6, 16, 10, 24, 14, 32, 54, 20, 66, 48, 26, 56, 90, 96, 34, 108, 76, 40, 126, 88, 138, 192, 100, 52, 108, 56, 116, 420, 124, 192, 66, 340, 70, 216, 222, 152, 234, 240, 82, 420, 86, 176, 90, 552, 564, 192, 98, 200, 306, 104

Offset: 1

Omar E. Pol, Jul 30 2008

a(n) is also the area under the curve of the function pi(x) from prime(n) to prime(n+1), see the illustration of initial terms. This sequence is also the first differences of A152535. - Omar E. Pol, Nov 13 2013

			a(5)=10 because the 5th prime is 11 and the 6th prime is 13. The 5th gap between primes is 2, then a(5)=5*2=10.

Robert Israel, Table of n, a(n) for n = 1..10000
Omar E. Pol, Illustration of initial terms

Cf. A000040, A000720, A001223, A046933, A002386.

P:= [seq(ithprime(i),i=1..1001)]:
seq(n*(P[n+1]-P[n]),n=1..1000); # Robert Israel, Nov 26 2015

Table[n*(Prime[n+1] - Prime[n]), {n, 100}] (* T. D. Noe, Nov 14 2013 *)
With[{nn=60},Times@@@Thread[{Range[nn],Differences[Prime[Range[nn+1]]]}]] (* Harvey P. Dale, Dec 18 2018 *)

diff(v)=vector(#v-1, i, (v[i+1]-v[i])*i);
diff(primes(100)) \\ Altug Alkan, Nov 26 2015

a(n) = n*(A000040(n+1)-A000040(n)) = n*A001223(n).

a(n) = n*(1 + A046933(n)). [Omar E. Pol, Nov 16 2008]

Corrected definition and example. - Omar E. Pol, Nov 16 2008

Name and example corrected by Bob Selcoe and Robert Israel, Nov 26 2015

A168421 Small Associated Ramanujan Prime, p_(i-n).

Original entry on oeis.org

2, 7, 11, 17, 23, 29, 31, 37, 37, 53, 53, 59, 67, 79, 79, 89, 97, 97, 127, 127, 127, 127, 127, 137, 137, 149, 157, 157, 179, 179, 191, 191, 211, 211, 211, 223, 223, 223, 233, 251, 251, 257, 293, 293, 307, 307, 307, 307, 307, 331, 331, 331

Offset: 1

John W. Nicholson, Nov 25 2009

nonn

a(n) is the smallest prime p_(k+1-n) on the left side of the Ramanujan Prime Corollary, 2*p_(i-n) > p_i for i > k, where the n-th Ramanujan Prime R_n is the k-th prime p_k. [Comment clarified and shortened by Jonathan Sondow, Dec 20 2013]
Smallest prime number, a(n), such that if x >= a(n), then there are at least n primes between x and 2x exclusively.
This is very useful in showing the number of primes in the range [p_k, 2*p_(i-n)] is greater than or equal to 1. By taking into account the size of the gaps between primes in [p_(i-n),p_k], one can see that the average prime gap is about log(p_k) using the following R_n / (2*n) ~ log(R_n).
Proof of Corollary: See Wikipedia link
The number of primes until the next Ramanujan prime, R_(n+1), can be found in A190874.
Not the same as A124136.
A084140(n) is the smallest integer where ceiling ((A104272(n)+1)/2), a(n) is the next prime after A084140(n). - John W. Nicholson, Oct 09 2013
If a(n) is in A005382(k) then A005383(k) is a twin prime with the Ramanujan prime, A104272(n) = A005383(k) - 2, and A005383(k) = A168425(n). If this sequence has an infinite number of terms in A005382, then the twin prime conjecture can be proved. - John W. Nicholson, Dec 05 2013
Except for A000101(1)=3 and A000101(2)=5, A000101(k) = a(n). Because of the large size of a gap, there are many repeats of the prime number in this sequence. - John W. Nicholson, Dec 10 2013
For some n and k, we see that a(n) = A104272(k) as to form a chain of primes similar to a Cunningham chain. For example (and the first example), a(2) = 7, links A104272(2) = 11 = a(3), links A104272(3) = 17 = a(4), links A104272(4) = 29 = a(6), links A104272(6) = 47. Note that the links do not have to be of a form like q = 2*p+1 or q = 2*p-1. - John W. Nicholson, Dec 14 2013
Srinivasan's Lemma (2014): p_(k-n) < (p_k)/2 if R_n = p_k and n > 1. Proof: By the minimality of R_n, the interval ((p_k)/2,p_k] contains exactly n primes, so p_(k-n) < (p_k)/2. - Jonathan Sondow, May 10 2014
In spite of the name Small Associated Ramanujan Prime, a(n) is not a Ramanujan prime for many values of n. - Jonathan Sondow, May 10 2014
Prime index of a(n), pi(a(n)) = i-n, is equal to A179196(n) - n + 1. - John W. Nicholson, Sep 15 2015
All maximal prime pairs in A002386 and A000101 are bounded by, for a particular n and i, the prime A104272(n) and twice a prime in A000040() following a(n). This means the gap between maximal prime pair cannot be more than twice the prior maximal prime gap. - John W. Nicholson, Feb 07 2019

			For n=10, the n-th Ramanujan prime is A104272(n)= 97, the value of k = 25, so i is >= 26, i-n >= 16, the i-n prime is 53, and 2*53 = 106. This leaves the range [97, 106] for the 26th prime which is 101. In this example, 53 is the small associated Ramanujan prime.

T. D. Noe, Table of n, a(n) for n = 1..10000
J. Sondow, Ramanujan primes and Bertrand's postulate, arXiv:0907.5232 [math.NT], 2009-2010; Amer. Math. Monthly 116 (2009) 630-635.
J. Sondow, J. W. Nicholson, and T. D. Noe, Ramanujan Primes: Bounds, Runs, Twins, and Gaps, arXiv:1105.2249 [math.NT], 2011; J. Integer Seq. 14 (2011) Article 11.6.2.
J. Sondow, J. W. Nicholson, and T. D. Noe, Ramanujan Primes: Bounds, Runs, Twins, and Gaps, J. Integer Seq. 14 (2011) Article 11.6.2
Anitha Srinivasan, An upper bound for Ramanujan primes, Integers, 19 (2014), #A19
Wikipedia, Ramanujan Prime

Cf. A000101, A005382, A005383, A084139, A084140.
Cf. A104272, A124136, A168425, A179196, A190874.
Cf. A165959 (range size), A230147 (records).

nn = 100;
t = Table[0, {nn}];
Do[m = PrimePi[2n] - PrimePi[n]; If[0 < m <= nn, t[[m]] = n], {n, 15 nn}];
A084139 = Join[{1}, t];
a[n_] := NextPrime[A084139[[n]]];
Array[a, nn] (* Jean-François Alcover, Nov 07 2018, after T. D. Noe in A084139 *)

use ntheory ":all"; say next_prime((nth_ramanujan_prime($)+1) >> 1) for 1..100; # _Dana Jacobsen, Mar 02 2016

a(n) = prime(primepi(A104272(n)) + 1 - n).
a(n) = nextprime(A084139(n+1)), where nextprime(x) is the next prime > x. Note: some A084139(n) may be prime, therefore nextprime(x) not equal to x. - John W. Nicholson, Oct 11 2013
a(n) = nextprime(A084140(n)). - John W. Nicholson, Oct 11 2013

Extended by T. D. Noe, Nov 22 2010

A200503 Record (maximal) gaps between prime sextuplets (p, p+4, p+6, p+10, p+12, p+16).

Original entry on oeis.org

90, 15960, 24360, 1047480, 2605680, 2856000, 3605070, 4438560, 5268900, 17958150, 21955290, 23910600, 37284660, 40198200, 62438460, 64094520, 66134250, 70590030, 77649390, 83360970, 90070470, 93143820, 98228130, 117164040, 131312160, 151078830, 154904820

Offset: 1

Alexei Kourbatov, Nov 18 2011

Prime sextuplets (p, p+4, p+6, p+10, p+12, p+16) are densest permissible constellations of 6 primes. Average gaps between sextuplets (and, more generally, between prime k-tuples) can be deduced from the Hardy-Littlewood k-tuple conjecture and are O(log^6(p)). Maximal gaps may be significantly larger than average gaps; this sequence suggests that maximal gaps are O(log^7(p)).

A200504 lists initial primes in sextuplets preceding the maximal gaps. A233426 lists the corresponding primes at the end of the maximal gaps.

			The gap of 15960 between sextuplets with initial primes 97 and 16057 is a maximal gap - larger than any preceding gap; therefore a(2)=15960.

Martin Raab, Table of n, a(n) for n = 1..83 (terms 1..56 from Alexei Kourbatov, terms 57..71 from Norman Luhn).
G. H. Hardy and J. E. Littlewood, Some problems of 'Partitio numerorum'; III: on the expression of a number as a sum of primes, Acta Mathematica, Vol. 44, pp. 1-70, 1923.
Alexei Kourbatov, Maximal gaps between prime k-tuples
Alexei Kourbatov, Maximal gaps between prime k-tuples: a statistical approach, arXiv preprint arXiv:1301.2242 [math.NT], 2013 and J. Int. Seq. 16 (2013) #13.5.2
Alexei Kourbatov, Tables of record gaps between prime constellations, arXiv preprint arXiv:1309.4053 [math.NT], 2013.
Alexei Kourbatov, The distribution of maximal prime gaps in Cramer's probabilistic model of primes, arXiv preprint arXiv:1401.6959 [math.NT], 2014.
Alexei Kourbatov and Marek Wolf, Predicting maximal gaps in sets of primes, arXiv preprint arXiv:1901.03785 [math.NT], 2019.
Norman Luhn, Patterns of prime k-tuplets & the Hardy-Littlewood constants.
Norman Luhn, Record Gaps Between Prime Sextuplets.
Eric Weisstein's World of Mathematics, k-Tuple Conjecture

Cf. A022008 (prime sextuplets), A113274, A113404, A200504, A201596, A201598, A201062, A201073, A201051, A201251, A202281, A202361, A008407, A002386, A233426.

DeleteDuplicates[Differences[Select[Partition[Prime[Range[10^7]],6,1],Differences[#]=={4,2,4,2,4}&][[;;,1]]],GreaterEqual] (* The program generates the first 10 terms of the sequence. *) (* Harvey P. Dale, May 08 2025 *)

(1) Conjectured upper bound: gaps between prime sextuplets (p, p+4, p+6, p+10, p+12, p+16) are smaller than 0.058*(log p)^7, where p is the prime at the end of the gap.
(2) Estimate for the actual size of the maximal gap that ends at p: maximal gap = a(log(p/a)-1/3), where a = 0.058*(log p)^6 is the average gap between sextuplets near p, as predicted by the Hardy-Littlewood k-tuple conjecture.
Formulas (1) and (2) are asymptotically equal as p tends to infinity. However, (1) yields values greater than all known gaps, while (2) yields "good guesses" that may be either above or below the actual size of maximal gaps. Both formulas (1) and (2) are derived from the Hardy-Littlewood k-tuple conjecture via probability-based heuristics relating the expected maximal gap size to the average gap. Neither of the formulas has a rigorous proof (the k-tuple conjecture itself has no formal proof either). In both formulas, the constant ~0.058 is reciprocal to the Hardy-Littlewood 6-tuple constant 17.2986...

A201051 Record (maximal) gaps between prime septuplets (p, p+2, p+6, p+8, p+12, p+18, p+20).

Original entry on oeis.org

165690, 903000, 10831800, 13773480, 22813770, 31090080, 43751820, 60881310, 86746170, 118516860, 239951250, 281573040, 359932650, 384903750, 518385000, 902801550, 1027007520, 1086331680, 1329198570, 2176467090

Offset: 1

Alexei Kourbatov, Nov 28 2011

Prime septuplets (p, p+2, p+6, p+8, p+12, p+18, p+20) are one of the two types of densest permissible constellations of 7 primes (A022009 and A022010). Average gaps between prime k-tuples can be deduced from the Hardy-Littlewood k-tuple conjecture and are O(log^k(p)), with k=7 for septuplets. If a gap is larger than any preceding gap, we call it a maximal gap, or a record gap. Maximal gaps may be significantly larger than average gaps; this sequence suggests that maximal gaps are O(log^8(p)).

A201249 lists initial primes p in septuplets (p, p+2, p+6, p+8, p+12, p+18, p+20) preceding the maximal gaps. A233425 lists the corresponding primes at the end of the maximal gaps.

			The gap of 165690 between septuplets starting at p=11 and p=165701 is the very first gap, so a(1)=165690. The gap of 903000 between septuplets starting at p=165701 and p=1068701 is a maximal gap - larger than any preceding gap; therefore a(2)=903000. The next gap of 10831800 is again a maximal gap, so a(3)=10831800. The next gap is smaller, so it does not contribute to the sequence.

Alexei Kourbatov, Table of n, a(n) for n = 1..36
Tony Forbes and Norman Luhn, Prime k-tuplets
G. H. Hardy and J. E. Littlewood, Some problems of 'Partitio numerorum'; III: On the expression of a number as a sum of primes, Acta Math., Vol. 44, No. 1 (1923), pp. 1-70.
Alexei Kourbatov, Maximal gaps between prime k-tuples
Alexei Kourbatov, Maximal gaps between prime k-tuples: a statistical approach, arXiv preprint arXiv:1301.2242 [math.NT], 2013 and J. Int. Seq. 16 (2013) #13.5.2
Alexei Kourbatov, Tables of record gaps between prime constellations, arXiv preprint arXiv:1309.4053 [math.NT], 2013.
Alexei Kourbatov, The distribution of maximal prime gaps in Cramer's probabilistic model of primes, arXiv preprint arXiv:1401.6959 [math.NT], 2014.
Norman Luhn, Record Gaps Between Prime Septuplets, up to 10^17
Eric Weisstein's World of Mathematics, k-Tuple Conjecture

Cf. A022009 (prime septuplets p, p+2, p+6, p+8, p+12, p+18, p+20), A113274, A113404, A200503, A201062, A201073, A201596, A201598, A201251, A202281, A202361, A201249, A002386, A233425.

Gaps between prime septuplets (p, p+2, p+6, p+8, p+12, p+18, p+20) are smaller than 0.02*(log p)^8, where p is the prime at the end of the gap. There is no rigorous proof of this formula. The O(log^8(p)) growth rate is suggested by numerical data and heuristics based on probability considerations.

cp's OEIS Frontend

A005669 Indices of primes where largest gap occurs.

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A111870 Prime p with prime gap q - p of n-th record merit, where q is smallest prime larger than p and the merit of a prime gap is (q-p)/log(p).

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A113274 Record gaps between twin primes.

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A014320 The next new gap between successive primes.

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A111871 Prime gaps q-p with n-th record merit referred to in A111870.

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A001632 Smallest prime p such that there is a gap of 2n between p and previous prime.

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A141042 Product of n and the n-th gap between primes: a(n) = n*A001223(n).

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