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 A362084 #13 Apr 19 2023 08:04:28
%S A362084 1,2,7,28,145,896,6328,50212,441489,4248370,44306306,496991848,
%T A362084 5959111223,75977511442,1025441134747,14594189335496,218290221112929,
%U A362084 3421314388169988,56043004143343843,957209642080023286,17011439135301438016,313980693855333453740
%N A362084 a(n) = Sum_{k=0..n} (-1)^k * binomial(-2,k) * binomial(n*k,n-k).
%H A362084 Seiichi Manyama, <a href="/A362084/b362084.txt">Table of n, a(n) for n = 0..493</a>
%F A362084 a(n) = Sum_{k=0..n} (k+1) * binomial(n*k,n-k).
%F A362084 a(n) = [x^n] 1/(1 - x*(1+x)^n)^2.
%o A362084 (PARI) a(n) = sum(k=0, n, (k+1)*binomial(n*k, n-k));
%Y A362084 Column k=2 of A362079.
%Y A362084 Cf. A099237.
%K A362084 nonn
%O A362084 0,2
%A A362084 _Seiichi Manyama_, Apr 08 2023