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.

Showing 1-10 of 19 results. Next

A333254 Lengths of maximal runs in the sequence of prime gaps (A001223).

Original entry on oeis.org

1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Gus Wiseman, Mar 20 2020

Keywords

Comments

Prime gaps are differences between adjacent prime numbers.
Also lengths of maximal arithmetic progressions of consecutive primes.

Examples

			The prime gaps split into the following runs: (1), (2,2), (4), (2), (4), (2), (4), (6), (2), (6), (4), (2), (4), (6,6), (2), (6), (4), ...
		

Crossrefs

The version for A000002 is A000002. Similarly for A001462.
The unequal version is A333216.
The weakly decreasing version is A333212.
The weakly increasing version is A333215.
The strictly decreasing version is A333252.
The strictly increasing version is A333253.
Positions of first appearances are A335406.
The first term of the first length-n arithmetic progression of consecutive primes is A006560(n), with index A089180(n).
Prime gaps are A001223.
Positions of adjacent equal prime gaps are A064113.
Positions of adjacent unequal prime gaps are A333214.

Programs

  • Maple
    p:= 3: t:= 1: R:= NULL: s:= 1: count:= 0:
    for i from 2 while count < 100 do
      q:= nextprime(p);
      g:= q-p; p:= q;
      if g = t then s:= s+1
      else count:= count+1; R:= R, s; t:= g; s:= 1;
      fi
    od:
    R; # Robert Israel, Jan 06 2021
  • Mathematica
    Length/@Split[Differences[Array[Prime,100]],#1==#2&]//Most

Formula

Partial sums are A333214.

A033451 Initial prime in set of 4 consecutive primes with common difference 6.

Original entry on oeis.org

251, 1741, 3301, 5101, 5381, 6311, 6361, 12641, 13451, 14741, 15791, 15901, 17471, 18211, 19471, 23321, 26171, 30091, 30631, 53611, 56081, 62201, 63691, 71341, 75521, 77551, 78791, 80911, 82781, 83431, 84431, 89101, 89381, 91291, 94421
Offset: 1

Views

Author

Keywords

Comments

Primes p such that p, p+6, p+12, p+18 are consecutive primes.
It is conjectured that there exist arbitrarily long sequences of consecutive primes in arithmetic progression. As of March 2013 the record is 10 primes.
Note that the Green and Tao reference is about arithmetic progressions that are not necessarily consecutive. - Michael B. Porter, Mar 05 2013
Subsequence of A023271. - R. J. Mathar, Nov 04 2006
All terms p == 1 (mod 10) and hence p+24 are always divisible by 5. - Zak Seidov, Jun 20 2015
Subsequence of A054800, with which is coincides up to a(24), but a(25) = A054800(26). - M. F. Hasler, Oct 26 2018

Examples

			251, 257, 263, 269 are consecutive primes: 257 = 251 + 6, 263 = 251 + 12, 269 = 251 + 18.
		

Crossrefs

Intersection of A054800 and A023271.
Analogous sequences [with common difference in square brackets]: A033447 [12], A033448 [18], A052242 [24], A052243 [30], A058252 [36], A058323 [42], A067388[48].
Subsequence of A047948.

Programs

  • Maple
    N:=10^5: # to get all terms <= N.
    Primes:=select(isprime,[seq(i,i=3..N+18,2)]):
    Primes[select(t->[Primes[t+1]-Primes[t], Primes[t+2]-Primes[t+1],
    Primes[t+3]-Primes[t+2]]=[6,6,6], [$1..nops(Primes)-3])]; # Muniru A Asiru, Aug 04 2017
  • Mathematica
    A033451 = Reap[ For[p = 2, p < 100000, p = NextPrime[p], p2 = NextPrime[p]; If[p2 - p == 6, p3 = NextPrime[p2]; If[p3 - p2 == 6, p4 = NextPrime[p3]; If[p4 - p3 == 6, Sow[p]]]]]][[2, 1]] (* Jean-François Alcover, Jun 28 2012 *)
    Transpose[Select[Partition[Prime[Range[16000]],4,1],Union[ Differences[ #]] == {6}&]][[1]] (* Harvey P. Dale, Jun 17 2014 *)
  • PARI
    p=2;q=3;r=5;forprime(s=7,1e4,if(s-p==18 && s-q==12 && s-r==6, print1(p", ")); p=q;q=r;r=s) \\ Charles R Greathouse IV, Feb 14 2013

Formula

a(n) = A000040(A090832(n)). - Zak Seidov, Jun 20 2015

A054819 First term of weak prime quartet: p(m+1)-p(m) < p(m+2)-p(m+1) < p(m+3)-p(m+2).

Original entry on oeis.org

17, 41, 79, 107, 227, 281, 311, 347, 349, 379, 397, 439, 461, 499, 569, 641, 673, 677, 827, 857, 881, 907, 1031, 1061, 1091, 1187, 1229, 1277, 1301, 1319, 1367, 1427, 1429, 1451, 1487, 1489, 1549, 1607, 1619, 1621, 1697, 1877, 1997, 2027, 2087, 2153
Offset: 1

Views

Author

Henry Bottomley, Apr 10 2000

Keywords

Examples

			From _Gus Wiseman_, May 31 2020: (Start)
The first 10 strictly increasing prime gap quartets:
   17   19   23   29
   41   43   47   53
   79   83   89   97
  107  109  113  127
  227  229  233  239
  281  283  293  307
  311  313  317  331
  347  349  353  359
  349  353  359  367
  379  383  389  397
(End)
		

Crossrefs

Prime gaps are A001223.
Second prime gaps are A036263.
Strictly decreasing prime gap quartets are A335278.
Strictly increasing prime gap quartets are A335277.
Equal prime gap quartets are A090832.
Weakly increasing prime gap quartets are A333383.
Weakly decreasing prime gap quartets are A333488.
Unequal prime gap quartets are A333490.
Partially unequal prime gap quartets are A333491.
Positions of adjacent equal prime gaps are A064113.
Positions of strict ascents in prime gaps are A258025.
Positions of strict descents in prime gaps are A258026.
Positions of adjacent unequal prime gaps are A333214.
Positions of weak ascents in prime gaps are A333230.
Positions of weak descents in prime gaps are A333231.
Lengths of maximal weakly decreasing sequences of prime gaps are A333212.
Lengths of maximal strictly increasing sequences of prime gaps are A333253.

Programs

  • Mathematica
    wpqQ[lst_]:=Module[{diffs=Differences[lst]},diffs[[1]]Harvey P. Dale, Jun 12 2012 *)
    ReplaceList[Array[Prime,100],{_,x_,y_,z_,t_,_}/;y-xx] (* Gus Wiseman, May 31 2020 *)

Formula

a(n) = prime(A335277(n)). - Gus Wiseman, May 31 2020

A054804 First term of strong prime quartets: prime(m+1)-prime(m) > prime(m+2)-prime(m+1) > prime(m+3)-prime(m+2).

Original entry on oeis.org

31, 61, 89, 211, 271, 293, 449, 467, 607, 619, 709, 743, 839, 863, 919, 1069, 1291, 1409, 1439, 1459, 1531, 1637, 1657, 1669, 1723, 1759, 1777, 1831, 1847, 1861, 1979, 1987, 2039, 2131, 2311, 2357, 2371, 2447, 2459, 2477, 2503, 2521, 2557, 2593, 2633
Offset: 1

Views

Author

Henry Bottomley, Apr 10 2000

Keywords

Comments

Primes preceding the first member of pairs of consecutive primes in A051634 ("strong primes"), see example. (A051634 lists the middle member of the triplets, here we list the first member of the quadruplets.) - M. F. Hasler, Oct 27 2018, corrected thanks to Gus Wiseman, Jun 01 2020.

Examples

			The first 10 strictly decreasing prime gap quartets:
   31  37  41  43
   61  67  71  73
   89  97 101 103
  211 223 227 229
  271 277 281 283
  293 307 311 313
  449 457 461 463
  467 479 487 491
  607 613 617 619
  619 631 641 643
For example, the primes (211,223,227,229) have differences (12,4,2), which are strictly decreasing, so 211 is in the sequence.
The second and third term of each quadruplet are consecutive terms in A051634: this is a characteristic property of this sequence. - _M. F. Hasler_, Jun 01 2020
		

Crossrefs

Prime gaps are A001223.
Second prime gaps are A036263.
All of the following use prime indices rather than the primes themselves:
- Strictly decreasing prime gap quartets are A335278.
- Strictly increasing prime gap quartets are A335277.
- Equal prime gap quartets are A090832.
- Weakly increasing prime gap quartets are A333383.
- Weakly decreasing prime gap quartets are A333488.
- Unequal prime gap quartets are A333490.
- Partially unequal prime gap quartets are A333491.
- Adjacent equal prime gaps are A064113.
- Strict ascents in prime gaps are A258025.
- Strict descents in prime gaps are A258026.
- Adjacent unequal prime gaps are A333214.
- Weak ascents in prime gaps are A333230.
- Weak descents in prime gaps are A333231.
Maximal weakly increasing intervals of prime gaps are A333215.
Maximal strictly decreasing intervals of prime gaps are A333252.

Programs

  • Maple
    primes:= select(isprime,[seq(i,i=3..10000,2)]):
    L:=  primes[2..-1]-primes[1..-2]:
    primes[select(t -> L[t+2] < L[t+1] and L[t+1] < L[t], [$1..nops(L)-2])]; # Robert Israel, Jun 28 2018
  • Mathematica
    ReplaceList[Array[Prime,100],{_,x_,y_,z_,t_,_}/;y-x>z-y>t-z:>x] (* Gus Wiseman, May 31 2020 *)
    Select[Partition[Prime[Range[400]],4,1],Max[Differences[#,2]]<0&][[All,1]] (* Harvey P. Dale, Jan 12 2023 *)

Formula

a(n) = prime(A335278(n)). - Gus Wiseman, May 31 2020

A333216 Lengths of maximal subsequences without adjacent equal terms in the sequence of prime gaps.

Original entry on oeis.org

2, 13, 21, 3, 7, 8, 1, 18, 29, 5, 3, 8, 11, 31, 4, 20, 3, 7, 5, 19, 21, 32, 1, 19, 48, 19, 29, 32, 7, 38, 1, 43, 12, 33, 46, 6, 16, 8, 4, 34, 15, 1, 19, 7, 1, 23, 28, 30, 22, 8, 1, 7, 1, 52, 14, 56, 10, 26, 2, 30, 65, 5, 71, 12, 44, 39, 37, 6, 19, 47, 11, 10
Offset: 1

Views

Author

Gus Wiseman, Mar 15 2020

Keywords

Comments

Prime gaps are differences between adjacent prime numbers.
Essentially the same as A145024. - R. J. Mathar, Mar 16 2020

Examples

			The prime gaps split into the following subsequences without adjacent equal terms: (1,2), (2,4,2,4,2,4,6,2,6,4,2,4,6), (6,2,6,4,2,6,4,6,8,4,2,4,2,4,14,4,6,2,10,2,6), (6,4,6), (6,2,10,2,4,2,12), (12,4,2,4,6,2,10,6), ...
		

Crossrefs

First differences of A064113.
The version for the Kolakoski sequence is A306323.
The weakly decreasing version is A333212.
The weakly increasing version is A333215.
The strictly decreasing version is A333252.
The strictly increasing version is A333253.
The equal version is A333254.

Programs

  • Mathematica
    Length/@Split[Differences[Array[Prime,100]],UnsameQ]//Most

Formula

Ones correspond to balanced prime quartets (A054800), so the sum of terms up to but not including the n-th one is A000720(A054800(n - 1)) = A090832(n).

A090839 Numbers k such that 6*k+1, 6*k+7, 6*k+13, 6*k+19 are consecutive primes.

Original entry on oeis.org

290, 550, 850, 1060, 2650, 3035, 3245, 5015, 5105, 8935, 10615, 11890, 12925, 13485, 13905, 14850, 15215, 15985, 17560, 17600, 18105, 19925, 20135, 21780, 23510, 24040, 25490, 28830, 31145, 34365, 36355, 38140, 38370, 42025, 43845, 46820, 47575, 48745, 49130, 50495, 53350
Offset: 1

Views

Author

Pierre CAMI, Dec 09 2003

Keywords

Comments

All terms are == 0 (mod 5). - Robert G. Wilson v, Dec 12 2017

Examples

			6*290 + 1 = 1741, 6*290 + 7 = 1747, 6*290 + 13 = 1753, 6*290 + 19 = 1759 and 1741, 1747, 1753, 1759 are consecutive primes, so 290 is a term.
		

Crossrefs

Programs

  • Mathematica
    Block[{nn = 50500, s}, s = Select[Prime@ Range@ PrimePi[6 (nn + 3) - 1], Divisible[(# + 1), 6] &]; Select[Range@ nn, And[AllTrue[#, PrimeQ], Count[s, q_ /; First[#] < q < Last@ #] == 0] &@ Map[6 # + 1 &, # + Range[0, 3]] &]] (* Michael De Vlieger, Dec 06 2017 *)
    fQ[n_] := Block[{p = {6n +1, 6n +7, 6n +13, 6n +19}}, Union@ PrimeQ@ p == {True} && NextPrime[6n +1, 3] == 6n +19]; Select[5 Range@ 10100, fQ] (* Robert G. Wilson v, Dec 12 2017 *)
    Select[(#-1)/6&/@Select[Partition[Prime[Range[30000]],4,1],Differences[#]=={6,6,6}&][[;;,1]],IntegerQ] (* Harvey P. Dale, Apr 05 2025 *)
  • PARI
    isok(n) = my(p,q,r); isprime(p=6*n+1) && ((q=6*n+7) == nextprime(p+1)) && ((r=6*n+13) == nextprime(q+1)) && (6*n+19 == nextprime(r+1)); \\ Michel Marcus, Sep 20 2019

Extensions

Missing term 5105 and more terms from Michel Marcus, Sep 20 2019

A090836 Numbers n such that 6*n+5, 6*n+11, 6*n+17, 6*n+23 are consecutive primes.

Original entry on oeis.org

41, 896, 1051, 2106, 2241, 2456, 2631, 2911, 3886, 4361, 9346, 10366, 12586, 13131, 13796, 14071, 14896, 15736, 15876, 17451, 19291, 20091, 20166
Offset: 1

Views

Author

Pierre CAMI, Dec 09 2003

Keywords

Examples

			6*41+5=251, 6*41+11=257, 6*41+17=263, 6*41+23=269; 251,257,263,269 are consecutive primes.
		

Crossrefs

Programs

  • Mathematica
    Select[(#-5)/6&/@Transpose[Select[Partition[Prime[Range[11500]],4,1], Union[Differences[#]]=={6}&]][[1]],IntegerQ] (* Harvey P. Dale, Nov 18 2013 *)

A090833 Numbers n such that 6n+5, 6n+11, 6n+17, 6n+23 are consecutive primes or 6n+1, 6n+7, 6n+13, 6n+19 are consecutive primes.

Original entry on oeis.org

41, 290, 550, 850, 896, 1051, 1060, 2106, 2241, 2456, 2631, 2650, 2911, 3035, 3245, 3886, 4361, 5015, 5105, 8935, 9346, 10366, 10615, 11890, 12586, 12925, 13131, 13485, 13796, 13905, 14071, 14850, 14896, 15215, 15736, 15876, 15985, 17451, 17560
Offset: 1

Views

Author

Pierre CAMI, Dec 09 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[20000],(PrimeQ[6#+5]&&Differences[NestList[ NextPrime[ #]&, 6 #+5,3]] =={6,6,6})||(PrimeQ[6#+1]&&Differences[NestList[NextPrime[#]&,6 #+1,3]]=={6,6,6})&] (* Harvey P. Dale, Sep 23 2016 *)
  • PARI
    p=2;q=3;r=5;forprime(s=7,1e5,if(s-p==18&&s-q==12&&s-r==6,print1(p\6", "));p=q;q=r;r=s) \\ Charles R Greathouse IV, Dec 27 2011

Extensions

a(19) from Charles R Greathouse IV, Dec 27 2011

A090834 Primes p such that p, p+6, p+12, p+18 are consecutive primes and p=6*k+5 for some k.

Original entry on oeis.org

251, 5381, 6311, 12641, 13451, 14741, 15791, 17471, 23321, 26171, 56081, 62201, 75521, 78791, 82781, 84431, 89381, 94421, 95261, 104711, 115751, 120551, 121001, 154061, 162251, 163841, 179801, 185051, 187361, 191021, 206021, 214451, 222311, 226631, 243521
Offset: 1

Views

Author

Pierre CAMI, Dec 09 2003

Keywords

Examples

			251,257,263,269 are consecutive primes,257=251+6,263=251+12,269=251+18 and 251=6*41+5
		

Crossrefs

Programs

  • Mathematica
    Transpose[Select[Partition[Prime[Range[30000]],4,1],Differences[#]=={6,6,6}&&IntegerQ[(#[[1]]-5)/6]&]][[1]] (* Harvey P. Dale, Dec 12 2015 *)

Extensions

More terms from Harvey P. Dale, Dec 12 2015

A090837 Primes p such that p, p+6, p+12, p+18 are consecutive primes and p = 6*k+1 for some k.

Original entry on oeis.org

1741, 3301, 5101, 6361, 15901, 18211, 19471, 30091, 30631, 53611, 63691, 71341, 77551, 80911, 83431, 89101, 91291, 95911, 105361, 105601, 108631, 119551, 120811, 130681, 141061, 144241, 152941, 172981, 186871, 206191, 218131, 228841, 230221, 252151, 263071, 280921, 285451
Offset: 1

Views

Author

Pierre CAMI, Dec 09 2003

Keywords

Examples

			1741, 1747, 1753, 1759 are consecutive primes, 1747 = 1741 + 6, 1753 = 1741 + 12, 1759 = 1741 + 18 and 1741 = 6 * 290 + 1.
		

Crossrefs

Programs

  • Maple
    filter:= p -> isprime(p) and nextprime(p) = p+6 and nextprime(p+6)=p+12 and nextprime(p+12)=p+18:
    select(filter, [seq(i,i=1..10^6,6)]); # Robert Israel, Nov 11 2020
  • PARI
    isok(p) = my(q,r,s); isprime(p) && ((p % 6) == 1) && ((q=nextprime(p+1)) == p+6) && ((r=nextprime(q+1)) == p+12) && ((s=nextprime(r+1)) == p+18); \\ Michel Marcus, Sep 20 2019

Extensions

More terms from Michel Marcus, Sep 20 2019
Showing 1-10 of 19 results. Next