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 A364099 #12 Jul 17 2023 00:58:17
%S A364099 1,3,4,5,6,7,8,11,10,11,12,13,14,20,16,17,18,19,20,27,22,23,24,25,29,
%T A364099 34,28,29,30,31,32,41,34,35,36,44,38,48,40,41,42,43,44,55,46,47,56,49,
%U A364099 50,62,52,57,54,55,56,69,58,68,60,61,62,76,64,65,66,67,68,92,80,71,72,73,74
%N A364099 Expansion of Sum_{k>0} k * x^k / (1 - x^(5*k-4)).
%F A364099 a(n) = (1/5) * Sum_{d | 5*n-4, d==1 (mod 5)} (d+4).
%F A364099 G.f.: Sum_{k>0} x^k / (1 - x^(5*k-4))^2.
%t A364099 a[n_] := DivisorSum[5*n - 4, # + 4 &, Mod[#, 5] == 1 &]/5; Array[a, 100] (* _Amiram Eldar_, Jul 17 2023 *)
%o A364099 (PARI) a(n) = sumdiv(5*n-4, d, (d%5==1)*(d+4))/5;
%Y A364099 Cf. A359238, A364095.
%K A364099 nonn
%O A364099 1,2
%A A364099 _Seiichi Manyama_, Jul 04 2023