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 A279888 #25 Jan 07 2025 01:58:56
%S A279888 0,1,42,569,4250,22006,88004,293369,845358,2186376,5145646,11282966,
%T A279888 23143198,45179324,83905292,150271993,258816840,433786483,704268402,
%U A279888 1119633944,1733618768,2640037170,3931060364,5777392406,8325691750,11873200964,16643954724,23133008124
%N A279888 a(n) = Sum_{k=1..n-1} sigma_3(k)*sigma_5(n-k).
%D A279888 Jean-Pierre Serre, A Course in Arithmetic, Springer-Verlag, 1973, Chapter VII, Section 4.
%H A279888 Seiichi Manyama, <a href="/A279888/b279888.txt">Table of n, a(n) for n = 1..1000</a>
%F A279888 a(n) = (11*sigma_9(n)-21*sigma_5(n)+10*sigma_3(n))/5040.
%t A279888 Table[Sum[If[k == 0, 0, DivisorSigma[3, k]] DivisorSigma[5, n - k], {k, 0, n - 1}], {n, 28}] (* _Michael De Vlieger_, Dec 22 2016 *)
%t A279888 a[n_] := (11 * DivisorSigma[9, n] - 21 * DivisorSigma[5, n] + 10 * DivisorSigma[3, n]) / 5040; Array[a, 30] (* _Amiram Eldar_, Jan 07 2025 *)
%o A279888 (PARI) a(n) = {my(f = factor(n)); (11 * sigma(f, 9) - 21 * sigma(f, 5) + 10 * sigma(f, 3)) / 5040;} \\ _Amiram Eldar_, Jan 07 2025
%Y A279888 Cf. A001158, A001160, A013957, A279917.
%K A279888 nonn
%O A279888 1,3
%A A279888 _Seiichi Manyama_, Dec 22 2016