A268930 -id:A268930 - cp's OEIS frontend

A268928 Record (maximal) gaps between primes of the form 6k - 1.

6, 12, 18, 30, 36, 42, 54, 60, 84, 126, 150, 162, 168, 246, 258, 318, 342, 354, 372, 408, 468, 534, 552, 600, 654, 762, 768, 798, 864, 894, 942, 960, 1068, 1224, 1302, 1320, 1344

Offset: 1

Alexei Kourbatov, Feb 15 2016

Dirichlet's theorem on arithmetic progressions and the GRH suggest that average gaps between primes of the form 6k - 1 below x are about phi(6)*log(x). This sequence shows that the record gap ending at p grows almost as fast as phi(6)*log^2(p). Here phi(n) is A000010, Euler's totient function; phi(6)=2.
Conjecture: a(n) < phi(6)*log^2(A268930(n)) almost always.
Conjecture: phi(6)*n^2/6 < a(n) < phi(6)*n^2 almost always. - Alexei Kourbatov, Nov 27 2019

			The first two primes of the form 6k-1 are 5 and 11, so a(1)=11-5=6. The next primes of this form are 17, 23, 29; the gaps 17-11 = 23-17 = 29-23 are not records so nothing is added to the sequence. The next prime of this form is 41 and the gap 41-29=12 is a new record, so a(2)=12.

Alexei Kourbatov, On the distribution of maximal gaps between primes in residue classes, arXiv:1610.03340 [math.NT], 2016.
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.

Cf. A007528, A268929 (primes preceding the maximal gaps), A268930 (primes at the end of the maximal gaps), A334543, A334544.

re = 0; s = 5; Reap[For[p = 11, p < 10^8, p = NextPrime[p], If[Mod[p, 6] != 5, Continue[]]; g = p - s; If[g > re, re = g; Print[g]; Sow[g]]; s = p]][[2, 1]] (* Jean-François Alcover, Dec 12 2018, from PARI *)

re=0; s=5; forprime(p=11, 1e8, if(p%6!=5, next); g=p-s; if(g>re, re=g; print1(g", ")); s=p)

a(n) = A268930(n) - A268929(n). - Alexei Kourbatov, Jun 15 2020.

Terms a(31)..a(37) from Alexei Kourbatov, Jun 15 2020

A268929 Primes 6k - 1 preceding the maximal gaps in A268928.

Original entry on oeis.org

5, 29, 113, 197, 521, 1109, 1733, 6389, 7349, 35603, 148517, 180797, 402593, 406907, 2339039, 5521721, 11157989, 20831267, 22440701, 27681263, 73451723, 241563407, 953758109, 1444257671, 1917281213, 6822753629, 15867286361, 28265029631, 40841579819, 177858259463

Offset: 1

Alexei Kourbatov, Feb 15 2016

nonn

Subsequence of A007528 and A334544.

A268928 lists the corresponding record gap sizes. See more comments there.

			The first two primes of the form 6k-1 are 5 and 11, so a(1)=5. The next primes of this form are 17, 23, 29; the gaps 17-11 = 23-17 = 29-23 are not records so nothing is added to the sequence. The next prime of this form is 41 and the gap 41-29=12 is a new record, so a(2)=29.

Alexei Kourbatov, Table of n, a(n) for n = 1..37
Alexei Kourbatov and Marek Wolf, Predicting maximal gaps in sets of primes, arXiv preprint arXiv:1901.03785 [math.NT], 2019.

Cf. A007528, A268928, A268930, A334543, A334544.

re=0; s=5; forprime(p=11, 1e8, if(p%6!=5, next); g=p-s; if(g>re, re=g; print1(s", ")); s=p)

a(n) = A268930(n) - A268928(n). - Alexei Kourbatov, Jun 15 2020.

A334545 Primes of the form 6k - 1 at the end of first-occurrence gaps in A334543.

Original entry on oeis.org

11, 41, 131, 227, 383, 557, 1151, 1787, 4337, 6449, 7433, 8363, 9137, 12893, 35729, 37781, 58889, 59879, 97787, 105863, 130769, 148667, 153887, 180959, 220151, 328271, 402761, 407153, 416849, 542441, 780587, 1138367, 1294571, 1444463, 1463837, 1604951

Offset: 1

Alexei Kourbatov, May 05 2020

nonn

Subsequence of A007528. Contains A268930 as a subsequence. First differs from A268930 at a(5)=383.

A334543 lists the corresponding gap sizes; see more comments there.

			The first two primes of the form 6k-1 are 5 and 11, so we have a(1)=11. The next primes of this form are 17, 23, 29; the gaps 17-11 = 23-17 = 29-23 have size 6 which already occurred before; so nothing is added to the sequence. The next prime of this form is 41 and the gap size 41-29=12 has not occurred before, so a(2)=41.

Alexei Kourbatov, Table of n, a(n) for n = 1..160
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. A007528, A014320, A058320, A268930, A330855, A334543, A334544.

isFirstOcc=vector(9999,j,1); s=5; forprime(p=11,1e8,if(p%6!=5,next); g=p-s; if(isFirstOcc[g/6], print1(p", "); isFirstOcc[g/6]=0); s=p)

a(n) = A334543(n) + A334544(n).

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A268928 Record (maximal) gaps between primes of the form 6k - 1.

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A268929 Primes 6k - 1 preceding the maximal gaps in A268928.

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A334545 Primes of the form 6k - 1 at the end of first-occurrence gaps in A334543.

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