A269421 -id:A269421 - cp's OEIS frontend

A269420 Record (maximal) gaps between primes of the form 8k + 3.

8, 24, 32, 40, 48, 72, 120, 144, 152, 176, 216, 264, 320, 400, 520, 592, 600, 824, 856, 872, 936, 992, 1064, 1072, 1112, 1336, 1392, 1408, 1584, 1720, 2080

Offset: 1

Alexei Kourbatov, Feb 25 2016

nonn

Dirichlet's theorem on arithmetic progressions suggests that average gaps between primes of the form 8k + 3 below x are about phi(8)*log(x). This sequence shows that the record gap ending at p grows almost as fast as phi(8)*log^2(p). Here phi(n) is A000010, Euler's totient function; phi(8)=4.
Conjecture: a(n) < phi(8)*log^2(A269422(n)) almost always.
A269421 lists the primes preceding the maximal gaps.
A269422 lists the corresponding primes at the end of the maximal gaps.

			The first two primes of the form 8k + 3 are 3 and 11, so a(1)=11-3=8. The next prime of this form is 19; the gap 19-11 is not a record so nothing is added to the sequence. The next prime of this form is 43 and the gap 43-19=24 is a new record, so a(2)=24.

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. A007520, A269421, A269422.

re=0; s=3; forprime(p=11, 1e8, if(p%8!=3, next); g=p-s; if(g>re, re=g; print1(g", ")); s=p)

A269422 Primes 8k + 3 at the end of the maximal gaps in A269420.

Original entry on oeis.org

11, 43, 211, 419, 739, 1259, 1427, 4931, 15619, 22483, 43283, 83843, 273643, 373859, 1543811, 5364683, 5769403, 20942083, 137650523, 251523163, 369353099, 426009691, 938379811, 1042909163, 1378015843, 1878781763, 11474651731, 12402607739, 15931940483, 51025311059, 144309633179

Offset: 1

Alexei Kourbatov, Feb 25 2016

nonn

Subsequence of A007520.

A269420 lists the corresponding record gap sizes. See more comments there.

			The first two primes of the form 8k + 3 are 3 and 11, so a(1)=11. The next prime of this form is 19; the gap 19-11 is not a record so nothing is added to the sequence. The next prime of this form is 43 and the gap 43-19=24 is a new record, so a(2)=43.

Alexei Kourbatov and Marek Wolf, Predicting maximal gaps in sets of primes, arXiv preprint arXiv:1901.03785 [math.NT], 2019.

Cf. A007520, A269420, A269421.

re=0; s=3; forprime(p=11, 1e8, if(p%8!=3, next); g=p-s; if(g>re, re=g; print1(p", ")); s=p)

cp's OEIS Frontend

A269420 Record (maximal) gaps between primes of the form 8k + 3.

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