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 A368537 #8 Dec 29 2023 08:06:45
%S A368537 0,1,18,309,5828,123230,2913126,76405854,2205340936,69523722855,
%T A368537 2377899710410,87721897714891,3472488925101516,146833416409808492,
%U A368537 6605726035373765678,315051237815279406540,15879038919798268666896,843348814519524716426685
%N A368537 a(n) = Sum_{k=1..n} binomial(k+2,3) * n^k.
%F A368537 a(n) = [x^n] n*x /((1-x) * (1-n*x)^4).
%F A368537 a(n) = n * (n^n * (n^6-7*n^4+5*n^3+12*n^2-11*n-6) + 6)/(6 * (n-1)^4) for n > 1.
%o A368537 (PARI) a(n) = sum(k=1, n, binomial(k+2, 3)*n^k);
%Y A368537 Cf. A062806, A368536.
%Y A368537 Cf. A368527.
%K A368537 nonn,easy
%O A368537 0,3
%A A368537 _Seiichi Manyama_, Dec 29 2023