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 A366613 #10 Jan 11 2024 15:50:57
%S A366613 7,60,224,1736,6048,49920,136724,1107792,3718400,27060480,85449224,
%T A366613 869499904,2136230474,15820920000,61359427584,461863805760,
%U A366613 1338408456700,13177159680000,33558717136896,301282248701952,863701914880000,6313641012910080,20863951122979048
%N A366613 Sum of the divisors of 5^n-1.
%H A366613 Max Alekseyev, <a href="/A366613/b366613.txt">Table of n, a(n) for n = 1..502</a>
%F A366613 a(n) = sigma(5^n-1) = A000203(A024049(n)).
%e A366613 a(3)=224 because 5^3-1 has divisors {1, 2, 4, 31, 62, 124}.
%p A366613 a:=n->numtheory[sigma](5^n-1):
%p A366613 seq(a(n), n=1..100);
%t A366613 DivisorSigma[1, 5^Range[30]-1]
%Y A366613 Cf. A024049, A000203, A057956, A059887, A074479, A143665, A218357, A295502, A366611, A366612.
%Y A366613 Cf. A075708, A366576, A366603, A366622, A366634, A366653, A366662, A102146, A366684, A366710.
%K A366613 nonn
%O A366613 1,1
%A A366613 _Sean A. Irvine_, Oct 14 2023