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 A366634 #8 Jan 20 2024 12:16:20
%S A366634 12,124,780,7812,33624,354640,1704240,18929096,97036800,800520192,
%T A366634 3958188480,56928231360,193778020824,1830926384640,11181115146240,
%U A366634 115997032277280,465294239722800,5175558387507200,22852200371636160,287850454432579584,1318081737957660000
%N A366634 Sum of the divisors of 7^n-1.
%H A366634 Max Alekseyev, <a href="/A366634/b366634.txt">Table of n, a(n) for n = 1..388</a>
%F A366634 a(n) = sigma(7^n-1) = A000203(A024075(n)).
%e A366634 a(5)=33624 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 16806}.
%p A366634 a:=n->numtheory[sigma](7^n-1):
%p A366634 seq(a(n), n=1..100);
%t A366634 DivisorSigma[1, 7^Range[30]-1]
%Y A366634 Cf. A024075, A000203, A057954, A059887, A074249, A218358, A366632, A366633, A366635.
%Y A366634 Cf. A075708, A366576, A366603, A366613, A366622, A366653, A366662, A102146, A366684, A366710.
%K A366634 nonn
%O A366634 1,1
%A A366634 _Sean A. Irvine_, Oct 14 2023