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 A363291 #14 Jul 08 2023 08:05:10
%S A363291 1,1,1,6,1,1,10,1,6,14,1,1,18,6,1,31,1,1,31,1,1,30,14,6,43,1,1,38,6,
%T A363291 18,42,1,1,60,1,14,71,1,6,54,1,1,67,31,1,62,18,1,84,1,30,79,1,6,74,1,
%U A363291 1,132,6,1,91,14,1,108,38,1,90,1,31,103,1,42,98,6,14,102,1,1,186,30,18,110,1,6,114,50,1
%N A363291 Sum of divisors of 4*n-1 of form 4*k+1.
%F A363291 a(n) = A050449(4*n-1).
%F A363291 G.f.: Sum_{k>0} (4*k-3) * x^(3*k-2) / (1 - x^(4*k-3)).
%t A363291 a[n_] := DivisorSum[4*n - 1, # &, Mod[#, 4] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Jul 08 2023 *)
%o A363291 (PARI) a(n) = sumdiv(4*n-1, d, (d%4==1)*d);
%Y A363291 Cf. A050449, A078703, A364082.
%K A363291 nonn
%O A363291 1,4
%A A363291 _Seiichi Manyama_, Jul 08 2023