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 A368526 #14 Dec 29 2023 08:05:42
%S A368526 0,1,18,282,4740,89355,1896846,45050852,1186829064,34391135205,
%T A368526 1087928669410,37322190255966,1380461544684300,54772368958008975,
%U A368526 2320775754168090870,104596636848116060040,4996700995031905899536,252208510175779038669321
%N A368526 a(n) = Sum_{k=1..n} k^2 * n^k.
%F A368526 a(n) = [x^n] n*x * (1+n*x)/((1-x) * (1-n*x)^3).
%F A368526 a(n) = n * (n+1) * (n^n * (n^3-3*n^2+2*n+1) - 1)/(n-1)^3 for n > 1.
%o A368526 (PARI) a(n) = sum(k=1, n, k^2*n^k);
%Y A368526 Cf. A062806, A303991, A368527.
%Y A368526 Cf. A368524.
%K A368526 nonn,easy
%O A368526 0,3
%A A368526 _Seiichi Manyama_, Dec 28 2023