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 A103968 #8 Feb 24 2020 08:08:05 %S A103968 1,13,74,1092,4864,59200,346112,4756752,19436692,251916288,1294876800, %T A103968 20786304000,79541043200,1073030266880,5303003316224,81061789640832, %U A103968 324992122224640,4102172934143680,20588576135708672,376372958524932096 %N A103968 Sigma((8^n - 1)/7), where sigma(n) is the sum of positive divisors of n. %H A103968 Amiram Eldar, <a href="/A103968/b103968.txt">Table of n, a(n) for n = 1..402</a> %F A103968 a(n) = A000203(A023001(n)). - _Amiram Eldar_, Feb 24 2020 %t A103968 DivisorSigma[1,(8^Range[20]-1)/7] (* _Harvey P. Dale_, Aug 21 2011 *) %Y A103968 Cf. A000203, A023001. %K A103968 nonn %O A103968 1,2 %A A103968 Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Mar 31 2005