cp's OEIS Frontend

A330854 Primes of the form 6k + 1 preceding the first-occurrence gaps in A330853.

%I A330854 #34 May 04 2020 21:25:38
%S A330854 7,19,43,241,283,1327,1489,1951,2389,4363,7789,10177,16759,22189,
%T A330854 24247,38461,40237,43441,69499,75403,100801,118927,171271,195541,
%U A330854 204163,250279,480169,577639,590437,1164607,1207699,1278817,1382221,1467937,1526659,1889803,2314369
%N A330854 Primes of the form 6k + 1 preceding the first-occurrence gaps in A330853.
%C A330854 Subsequence of A002476. First differs from A268926 in that that sequence does not include 283; all terms of A268926 are in this sequence but many terms of this sequence are not in A268926.
%H A330854 Alexei Kourbatov, <a href="/A330854/b330854.txt">Table of n, a(n) for n = 1..135</a>
%H A330854 Alexei Kourbatov and Marek Wolf, <a href="https://arxiv.org/abs/2002.02115">On the first occurrences of gaps between primes in a residue class</a>, arXiv preprint arXiv:2002.02115 [math.NT], 2020.
%F A330854 a(n) = A330855(n) - A330853(n).
%e A330854 The first two primes of the form 6k + 1 are 7 and 13, so a(1) = 7. The next prime of that form is 19, and the gap 19 - 13 = 6 already occurred; so a new term is not added to the sequence. The next prime of the form 6k + 1 is 31, and the gap 31 - 19 = 12 is occurring for the first time; therefore a(2) = 19.
%e A330854 The gap between 241 and the next prime of the form 6k + 1 (271) is 30. So 241 is in the sequence.
%e A330854 Although the gap between 283 and 307 is only 24 (which is less than 30), the gap is of a size not previously encountered. So 283 is in the sequence.
%o A330854 (PARI) isFirstOcc=vector(9999,j,1); s=7; forprime(p=13,1e8, if(p%6!=1,next); g=p-s; if(isFirstOcc[g/6], print1(s", "); isFirstOcc[g/6]=0); s=p)
%Y A330854 Cf. A002476, A014320, A058320, A330853 (gap sizes), A330855.
%K A330854 nonn
%O A330854 1,1
%A A330854 _Alexei Kourbatov_, Apr 27 2020