cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A113404 Record gaps between prime quadruplets.

Original entry on oeis.org

6, 90, 630, 660, 1170, 2190, 3780, 6420, 8940, 9030, 13260, 16470, 24150, 28800, 29610, 39990, 56580, 56910, 71610, 83460, 94530, 114450, 157830, 159060, 171180, 177360, 190500, 197910, 268050, 315840, 395520, 435240, 440910, 513570, 536010, 539310, 557340, 635130
Offset: 1

Views

Author

Bernardo Boncompagni, Oct 28 2005

Keywords

Comments

Prime quadruplets (p, p+2, p+6, p+8) are densest permissible constellations of 4 primes (A007530). By the Hardy-Littlewood k-tuple conjecture, average gaps between prime k-tuples are O(log^k(p)), with k=4 for quadruplets. If a gap is larger than all preceding gaps, 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 between prime quadruplets are O(log^5(p)). - Alexei Kourbatov, Jan 04 2012

Examples

			The first prime quadruplets are (5,7,11,13) and (11,13,17,19), so a(1)=11-5=6. The next quadruplet is (101,103,107,109), so a(2)=101-11=90. The following quadruplet is 191,193,197,199 so 90 remains the record and no terms are added.
		

Crossrefs

A229907 lists initial primes in quadruplets preceding the maximal gaps. A113403 lists the corresponding primes at the end of the maximal gaps. Cf. A008407, A007530.

Programs

  • Mathematica
    DeleteDuplicates[Differences[#[[4]]&/@Select[Partition[Prime[Range[10^7]],4,1],Differences[#] == {2,4,2}&]],GreaterEqual] (* The program generates the first 29 terms of the sequence. *) (* Harvey P. Dale, Aug 04 2024 *)

Formula

From Alexei Kourbatov, Jan 04 2012: (Start)
(1) Upper bound: gaps between prime quadruplets (p, p+2, p+6, p+8) are smaller than 0.241*(log p)^5, 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)-0.55), where a = 0.241*(log p)^4 is the average gap between quadruplets 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 ~0.241 is reciprocal to the Hardy-Littlewood 4-tuple constant 4.15118... (End)

Extensions

Terms 159060 to 635130 added by Alexei Kourbatov, Jan 04 2012

A049437 Primes p such that p+2 and p+8 are also primes but p+6 is not.

Original entry on oeis.org

3, 29, 59, 71, 149, 269, 431, 569, 599, 1031, 1061, 1229, 1289, 1319, 1451, 1619, 2129, 2339, 2381, 2549, 2711, 2789, 3299, 3539, 4019, 4049, 4091, 4649, 4721, 5099, 5441, 5519, 5639, 5741, 5849, 6269, 6359, 6569, 6701, 6959, 7211
Offset: 1

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Author

Keywords

Comments

p+4 is not prime here except for p=3.

Examples

			p=29 is the smallest prime so that p, p+2 and p+8 are consecutive primes.
		

Crossrefs

Subsequence of A001359. - R. J. Mathar, Feb 10 2013

Programs

  • Magma
    [p: p in PrimesUpTo(8000)| IsPrime(p+2) and IsPrime(p+8) and not IsPrime(p+6) ] // Vincenzo Librandi, Jan 28 2011
    
  • Maple
    select(p -> isprime(p) and isprime(p+2) and isprime(p+8) and not isprime(p+6), [3, seq(i,i=5..10000, 6)]); # Robert Israel, Nov 20 2017
  • Mathematica
    {3}~Join~Select[Partition[Prime@ Range[10^3], 3, 1], Differences@ # == {2, 6} &][[All, 1]] (* Michael De Vlieger, Nov 20 2017 *)
  • PARI
    lista(nn) = forprime(p=3, nn, if(isprime(p+2) && isprime(p+8) && !isprime(p+6), print1(p, ", "))) \\ Iain Fox, Nov 20 2017

A049438 p, p+6 and p+8 are all primes (A046138) but p+2 is not.

Original entry on oeis.org

23, 53, 131, 173, 233, 263, 563, 593, 653, 1013, 1223, 1283, 1601, 1613, 2333, 2543, 2963, 3323, 3533, 3761, 3911, 3923, 4013, 4211, 4253, 4643, 4793, 5003, 5273, 5471, 5843, 5861, 6263, 6353, 6563, 6653, 6863, 7121, 7451, 7481, 7541, 7583
Offset: 1

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Author

Keywords

Crossrefs

Subsequence of A031924. - R. J. Mathar, Jun 15 2013

Programs

  • Mathematica
    Select[Prime@ Range[10^3], MatchQ[Boole@ PrimeQ@ {# + 2, # + 6, # + 8}, {0, 1, 1}] &] (* Michael De Vlieger, Feb 05 2017 *)
  • PARI
    isok(p) = isprime(p) && !isprime(p+2) && isprime(p+6) && isprime(p+8); \\ Michel Marcus, Dec 13 2013

A173037 Numbers k such that k-4, k-2, k+2 and k+4 are prime.

Original entry on oeis.org

9, 15, 105, 195, 825, 1485, 1875, 2085, 3255, 3465, 5655, 9435, 13005, 15645, 15735, 16065, 18045, 18915, 19425, 21015, 22275, 25305, 31725, 34845, 43785, 51345, 55335, 62985, 67215, 69495, 72225, 77265, 79695, 81045, 82725, 88815, 97845
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Feb 07 2010

Keywords

Comments

Average k of the four primes in two twin prime pairs (k-4, k-2) and (k+2, k+4) which are linked by the cousin prime pair (k-2, k+2).
All terms are odd composites; except for a(1) they are multiples of 5.
Subsequence of A087679, of A087680 and of A164385.
All terms except for a(1) are multiples of 15. - Zak Seidov, May 18 2014
One of (k-1, k, k+1) is always divisible by 7. - Fred Daniel Kline, Sep 24 2015
Terms other than a(1) must be equivalent to 1 mod 2, 0 mod 3, 0 mod 5, and 0,+/-1 mod 7. Taken together, this requires terms other than a(1) to have the form 210k+/-15 or 210k+105. However, not all numbers of that form belong to this sequence. - Keith Backman, Nov 09 2023

Examples

			9 is a term because 9-4 = 5 is prime, 9-2 = 7 is prime, 9+2 = 11 is prime and 9+4 = 13 is prime.
		

Crossrefs

Programs

  • Magma
    [ p+4: p in PrimesUpTo(100000) | IsPrime(p) and IsPrime(p+2) and IsPrime(p+6) and IsPrime(p+8) ]; // Klaus Brockhaus, Feb 09 2010
    
  • Mathematica
    Select[Range[100000],AllTrue[#+{4,2,-2,-4},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jul 30 2015 *)
  • PARI
    is(n)=isprime(n-4) && isprime(n-2) && isprime(n+2) && isprime(n+4) \\ Charles R Greathouse IV, Sep 24 2015
    
  • Python
    from sympy import primerange
    def aupto(limit):
        p, q, r, alst = 2, 3, 5, []
        for s in primerange(7, limit+5):
            if p+2 == q and p+6 == r and p+8 == s: alst.append(p+4)
            p, q, r = q, r, s
        return alst
    print(aupto(10**5)) # Michael S. Branicky, Feb 03 2022

Formula

For n >= 2, a(n) = 15*A112540(n-1). - Michel Marcus, May 19 2014
From Jeppe Stig Nielsen, Feb 18 2020: (Start)
For n >= 2, a(n) = 30*A014561(n-1) + 15.
For n >= 2, a(n) = 10*A007811(n-1) + 5.
a(n) = A007530(n) + 4.
a(n) = A125855(n) + 5. (End)

Extensions

Edited and extended beyond a(9) by Klaus Brockhaus, Feb 09 2010

A053778 First of four consecutive primes that comprise two sets of twin primes.

Original entry on oeis.org

5, 11, 101, 137, 179, 191, 419, 809, 821, 1019, 1049, 1481, 1871, 1931, 2081, 2111, 2969, 3251, 3359, 3371, 3461, 4217, 4229, 4259, 5009, 5651, 5867, 6689, 6761, 6779, 6947, 7331, 7547, 8219, 8969, 9419, 9431, 9437, 10007, 11057, 11159, 11699, 12239
Offset: 1

Views

Author

Labos Elemer, Mar 24 2000

Keywords

Comments

These twins are not necessarily at the minimal distance as in A007530 (which is a subsequence).

Examples

			These primes initiate consecutive p quadruples as follows: [p,p+2,p+6k,p+6k+2]. For 6k=6,12,18,24,30,36,54 such a p =5,137,1931,9437,2968, 20441 and 48677 resp. Such a quadruple is [48677,48679,48731,48733], with [2,52,2] difference pattern.
		

Crossrefs

Programs

  • Mathematica
    Transpose[Select[Partition[Prime[Range[1500]],4,1],#[[4]]-#[[3]]== #[[2]]-#[[1]]== 2&]][[1]] (* Harvey P. Dale, Jul 07 2011 *)
  • PARI
    forprime( p=1,10^5, isprime(p+2) || next; isprime(nextprime(p+4)+2) && print1(p","))
    
  • PARI
    nextA053778(p)=until( isprime(nextprime(p+1)+2), until( p+2==p=nextprime(p+1),)); p-2
    
  • PARI
    p=0; A053778=vector(100,i, p=nextA053778(p+1))

Formula

A001359 primes for which A048614 is zero. Lesser of 2-twin primes after which the consecutive prime difference pattern (of A001223) is [2, 6k-2, 2] for some k.

Extensions

Edited by N. J. A. Sloane, Apr 13 2008, at the suggestion of M. F. Hasler.

A059925 Numbers n such that {n, n+2, n+6, n+8, n+30, n+32, n+36, n+38} are all prime.

Original entry on oeis.org

1006301, 2594951, 3919211, 9600551, 10531061, 108816311, 131445701, 152370731, 157131641, 179028761, 211950251, 255352211, 267587861, 557458631, 685124351, 724491371, 821357651, 871411361, 1030262081, 1103104361, 1282160021, 1381201271, 1427698631, 1432379951, 1443994001
Offset: 1

Views

Author

Martin Raab, Mar 03 2001

Keywords

Comments

Each term is the initial member of two prime quadruples (A007530) with the smallest possible difference of 30.

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[5582*10^4]],AllTrue[#+{2,6,8,30,32,36,38},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 13 2019 *)
  • PARI
    is(n)=my(v=[0,2,6,8,30,32,36,38]);for(i=1,8, if(!isprime(n+v[i]), return(0)));1 \\ Charles R Greathouse IV, Jun 18 2013

Formula

a(n) = 2 (mod 21). - Hugo Pfoertner, Dec 29 2024

Extensions

For clarity, replaced definition by a comment from Charles R Greathouse IV. - N. J. A. Sloane, Nov 26 2020

A136162 List of prime quadruplets {p, p+2, p+6, p+8}.

Original entry on oeis.org

5, 7, 11, 13, 11, 13, 17, 19, 101, 103, 107, 109, 191, 193, 197, 199, 821, 823, 827, 829, 1481, 1483, 1487, 1489, 1871, 1873, 1877, 1879, 2081, 2083, 2087, 2089, 3251, 3253, 3257, 3259, 3461, 3463, 3467, 3469, 5651, 5653, 5657, 5659, 9431, 9433, 9437
Offset: 1

Views

Author

Harry J. Smith, Dec 17 2007

Keywords

Comments

{11, 13, 17, 19} is the only prime quadruplet {p, p+2, p+6, p+8} of the form {Q-4, Q-2, Q+2, Q+4} where Q is a product of a pair of twin primes {q, q+2} (for prime q = 3) because numbers Q-2 and Q+4 are for q>3 composites of the form 3*(12*k^2-1) and 3*(12*k^2+1) respectively (k is an integer). Conjecture: {11, 13, 17, 19} is the only prime quadruplet {p, p+2, p+6, p+8} of the form {q*(nextprime(q))-4, q*( nextprime(q))-2, q*( nextprime(q))+2, q*( nextprime(q))+4} where q is a prime (for prime q = 3). - Jaroslav Krizek, Jul 07 2017

Crossrefs

Cf. A007530 (1st quadrisection).

Programs

  • Mathematica
    Map[Prime[Range @@ #] &, MapAt[# + 1 &, SequencePosition[Differences@ Prime@ Range@ 1200, {2, 4, 2}], {All, -1}]] // Flatten (* Michael De Vlieger, Jul 11 2017 *)
  • PARI
    {forprime(p1=0,70000,p2=p1+2;if(!isprime(p2),next;);p3=p1+6;if(!isprime(p3),next;);p4=p1+8;if(!isprime(p4),next;);print1(p1,",",p2,",",p3,",",p4,","))}
    
  • PARI
    q=[0,0,0,0];i=0;forprime(p=5,1e4,(q[i%4+1]=p)==8+q[i++%4+1]&&print1(vecsort(q)","))  \\ M. F. Hasler, Apr 20 2013

Formula

[a(4n-3),a(4n-2),a(4n-1),a(4n)] = A007530(n) + [0,2,6,8], for all n>0. - M. F. Hasler, Apr 20 2013

A125855 Numbers k such that k+1, k+3, k+7 and k+9 are all primes.

Original entry on oeis.org

4, 10, 100, 190, 820, 1480, 1870, 2080, 3250, 3460, 5650, 9430, 13000, 15640, 15730, 16060, 18040, 18910, 19420, 21010, 22270, 25300, 31720, 34840, 43780, 51340, 55330, 62980, 67210, 69490, 72220, 77260, 79690, 81040, 82720, 88810, 97840
Offset: 1

Views

Author

Artur Jasinski, Dec 12 2006

Keywords

Comments

It seems that, with the exception of 4, all terms are multiples of 10. - Emeric Deutsch, Dec 24 2006
In fact, all terms except 4 are congruent to 10 (mod 30). - Franklin T. Adams-Watters, Jun 05 2014
For n > 1: a(n) = 10*A007811(n-1). - Reinhard Zumkeller, Jul 18 2014 [Comment corrected by Jens Kruse Andersen, Jul 19 2014]

Examples

			For k = 10, the numbers 10 + 1 = 11, 10 + 3 = 13, 10 + 7 = 17, 10 + 9 = 19 are prime. - _Marius A. Burtea_, May 18 2019
		

Crossrefs

Cf. A010051, A245304 (subsequence), A007811.

Programs

  • Haskell
    a125855 n = a125855_list !! (n-1)
    a125855_list = map (pred . head) $ filter (all (== 1) . map a010051') $
       iterate (zipWith (+) [1, 1, 1, 1]) [1, 3, 7, 9]
    -- Reinhard Zumkeller, Jul 18 2014
    
  • Magma
    [n:n in [1..100000]| IsPrime(n+1) and IsPrime(n+3) and IsPrime(n+7) and IsPrime(n+9)]; // Marius A. Burtea, May 18 2019
    
  • Maple
    a:=proc(n): if isprime(n+1)=true and isprime(n+3)=true and isprime(n+7)=true and isprime(n+9)=true then n else fi end: seq(a(n),n=1..500000); # Emeric Deutsch, Dec 24 2006
  • Mathematica
    Do[If[(PrimeQ[x + 1]) && (PrimeQ[x + 3]) && (PrimeQ[x + 7]) && (PrimeQ[x + 9]), Print[x]], {x, 1, 10000}]
    (* Second program *)
    Select[Range[10^5], Times @@ Boole@ Map[PrimeQ, # + {1, 3, 7, 9}] == 1 &] (* Michael De Vlieger, Jun 12 2017 *)
    Select[Range[100000],AllTrue[#+{1,3,7,9},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 02 2018 *)
  • PARI
    is(n) = my(v=[1, 3, 7, 9]); for(t=1, #v, if(!ispseudoprime(n+v[t]), return(0))); 1 \\ Felix Fröhlich, May 18 2019

Formula

a(n) = A007530(n) - 1. - R. J. Mathar, Jun 14 2017

Extensions

More terms from Emeric Deutsch, Dec 24 2006

A090258 Last term of prime quadruples.

Original entry on oeis.org

13, 19, 109, 199, 829, 1489, 1879, 2089, 3259, 3469, 5659, 9439, 13009, 15649, 15739, 16069, 18049, 18919, 19429, 21019, 22279, 25309, 31729, 34849, 43789, 51349, 55339, 62989, 67219, 69499, 72229, 77269, 79699, 81049, 82729, 88819, 97849
Offset: 1

Views

Author

Cino Hilliard, Jan 24 2004

Keywords

Crossrefs

Equals A064974 - 1.
Equals A007530 + 8.

Programs

  • Mathematica
    A090258 = Select[Range[9, 10^5 - 1, 2], Union[PrimeQ[# - {0, 2, 6, 8}]] == {True} &] (* Alonso del Arte, Aug 12 2012 *)
    Transpose[Select[Partition[Prime[Range[9500]],4,1],Differences[#]=={2,4,2}&]] [[4]] (* Harvey P. Dale, Nov 11 2013 *)
  • PARI
    quintpr(n) = { s=0; forprime(p=5,n, if(isprime(p+2) && isprime(p+6) && isprime(p+8), print1(p+8","); ) ); print(); print(s+.0) }

A047299 Numbers that are congruent to {0, 1, 3, 4, 6} mod 7.

Original entry on oeis.org

0, 1, 3, 4, 6, 7, 8, 10, 11, 13, 14, 15, 17, 18, 20, 21, 22, 24, 25, 27, 28, 29, 31, 32, 34, 35, 36, 38, 39, 41, 42, 43, 45, 46, 48, 49, 50, 52, 53, 55, 56, 57, 59, 60, 62, 63, 64, 66, 67, 69, 70, 71, 73, 74, 76, 77, 78
Offset: 1

Views

Author

Keywords

Comments

Nonnegative m such that floor(k*m^2/7) = k*floor(m^2/7), where k = 2 or 3. [Bruno Berselli, Dec 03 2015]
For k > 1 (A007530(k+1) - A007530(k))/30 is a term in this sequence. - Hugo Pfoertner, May 29 2020

Crossrefs

Cf. A007530 (prime quadruples).

Programs

Formula

G.f.: x^2*(1+2*x+x^2+2*x^3+x^4) / ( (x^4+x^3+x^2+x+1)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011
a(n) = floor((7n-5)/5). - Lorenz H. Menke, Jr., Jun 19 2013

Extensions

Formula and programs adapted to offset 1 by Michel Marcus, May 30 2020
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