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.
%I A359306 #16 Aug 16 2023 02:26:51 %S A359306 1,1,1,1,2,1,1,1,2,1,1,2,2,1,1,1,2,1,2,1,2,2,1,1,2,2,1,1,2,1,1,2,3,1, %T A359306 2,1,2,1,1,2,2,2,1,1,2,1,2,2,2,1,2,2,2,2,1,1,2,1,1,1,4,2,1,1,2,1,2,2, %U A359306 2,2,1,2,2,2,2,1,2,1,1,1,2,3,2,1,2,1,2,1,4,1 %N A359306 Number of divisors of 6*n-2 of form 6*k+1. %H A359306 Seiichi Manyama, <a href="/A359306/b359306.txt">Table of n, a(n) for n = 1..10000</a> %F A359306 a(n) = A279060(6*n-2). %F A359306 G.f.: Sum_{k>0} x^k/(1 - x^(6*k-2)). %F A359306 G.f.: Sum_{k>0} x^(4*k-3)/(1 - x^(6*k-5)). %t A359306 a[n_] := DivisorSum[6*n-2, 1 &, Mod[#, 6] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Aug 16 2023 *) %o A359306 (PARI) a(n) = sumdiv(6*n-2, d, d%6==1); %o A359306 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-x^(6*k-2)))) %o A359306 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^(4*k-3)/(1-x^(6*k-5)))) %Y A359306 Cf. A279060, A359305, A359307, A359308, A359309. %K A359306 nonn,easy %O A359306 1,5 %A A359306 _Seiichi Manyama_, Dec 25 2022