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 A366668 #14 Jan 05 2024 17:27:13
%S A366668 3,12,102,1344,10212,109104,1010004,10909104,105882372,1413350400,
%T A366668 10102223208,114737461440,1021097900424,10921790676000,
%U A366668 104844305394000,1355394166984704,10073631600468000,110177492439680640,1010002989998020008,10909090909090909104
%N A366668 Sum of the divisors of 10^n+1.
%H A366668 Max Alekseyev, <a href="/A366668/b366668.txt">Table of n, a(n) for n = 0..331</a>
%F A366668 a(n) = sigma(10^n+1) = A000203(A062397(n)).
%e A366668 a(3)=1344 because 10^3+1 has divisors {1, 7, 11, 13, 77, 91, 143, 1001}.
%p A366668 a:=n->numtheory[sigma](10^n+1):
%p A366668 seq(a(n), n=0..100);
%t A366668 DivisorSigma[1, 10^Range[0,19] + 1] (* _Paul F. Marrero Romero_, Nov 12 2023 *)
%Y A366668 Cf. A000203, A003021, A057934, A062397, A102146, A119704, A344897, A366666.
%K A366668 nonn
%O A366668 0,1
%A A366668 _Sean A. Irvine_, Oct 15 2023