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 A279917 #18 Jan 07 2025 01:41:00
%S A279917 0,1,162,6689,121250,1296406,9613604,54550049,252178758,992204376,
%T A279917 3424910566,10615778966,30047257318,78751366604,193075366412,
%U A279917 446840757793,982597838280,2066025009763,4171924730922,8127978871064,15324653827568,28059983210370
%N A279917 a(n) = Sum_{k=1..n-1} sigma_5(k)*sigma_7(n-k).
%H A279917 Seiichi Manyama, <a href="/A279917/b279917.txt">Table of n, a(n) for n = 1..1000</a>
%F A279917 a(n) = (sigma_13(n)+20*sigma_7(n)-21*sigma_5(n))/10080.
%t A279917 a[n_] := (DivisorSigma[13, n] + 20 * DivisorSigma[7, n] - 21 * DivisorSigma[5, n]) / 10080; Array[a, 25] (* _Amiram Eldar_, Jan 07 2025 *)
%o A279917 (PARI) a(n) = {my(f = factor(n)); (sigma(f, 13) + 20 * sigma(f, 7) - 21 * sigma(f, 5)) / 10080;} \\ _Amiram Eldar_, Jan 07 2025
%Y A279917 Cf. A001160, A013955, A013961, A279888.
%K A279917 nonn
%O A279917 1,3
%A A279917 _Seiichi Manyama_, Dec 23 2016