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 A364100 #15 Jul 17 2023 00:59:57
%S A364100 4,9,14,19,28,29,34,39,48,49,63,59,68,69,74,79,102,89,94,108,108,109,
%T A364100 133,119,128,129,134,139,181,149,168,159,168,169,203,179,188,198,194,
%U A364100 199,242,228,214,219,242,229,282,239,248,249,254,259,336,269,274,288,288,289,357,299,327,309,314,348
%N A364100 Sum of divisors of 5*n-1 of form 5*k+4.
%F A364100 a(n) = A284103(5*n-1).
%F A364100 G.f.: Sum_{k>0} (5*k-1) * x^k / (1 - x^(5*k-1)).
%t A364100 a[n_] := DivisorSum[5*n - 1, # &, Mod[#, 5] == 4 &]; Array[a, 100] (* _Amiram Eldar_, Jul 17 2023 *)
%o A364100 (PARI) a(n) = sumdiv(5*n-1, d, (d%5==4)*d);
%Y A364100 Cf. A364101, A364102, A364103.
%Y A364100 Cf. A284103, A359233, A364104.
%K A364100 nonn
%O A364100 1,1
%A A364100 _Seiichi Manyama_, Jul 04 2023