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 A359238 #15 Aug 23 2023 08:41:56 %S A359238 1,2,2,2,2,2,2,3,2,2,2,2,2,4,2,2,2,2,2,4,2,2,2,2,3,4,2,2,2,2,2,4,2,2, %T A359238 2,4,2,4,2,2,2,2,2,4,2,2,4,2,2,4,2,3,2,2,2,4,2,4,2,2,2,4,2,2,2,2,2,6, %U A359238 4,2,2,2,2,4,2,2,2,2,2,6,2,2,2,4,2,4,2,2,3,2 %N A359238 Number of divisors of 5*n-4 of form 5*k+1. %H A359238 Seiichi Manyama, <a href="/A359238/b359238.txt">Table of n, a(n) for n = 1..10000</a> %F A359238 a(n) = A001876(5*n-4). %F A359238 G.f.: Sum_{k>0} x^k/(1 - x^(5*k-4)). %t A359238 a[n_] := DivisorSum[5*n-4, 1 &, Mod[#, 5] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Aug 23 2023 *) %o A359238 (PARI) a(n) = sumdiv(5*n-4, d, d%5==1); %o A359238 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-x^(5*k-4)))) %Y A359238 Cf. A001876, A359233, A359236, A359237. %K A359238 nonn,easy %O A359238 1,2 %A A359238 _Seiichi Manyama_, Dec 22 2022