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 A376326 #13 Sep 20 2024 12:27:43
%S A376326 1,4,30,272,2737,29380,329614,3818540,45329440,548511612,6740687924,
%T A376326 83898110660,1055441468145,13398494365088,171422870731600,
%U A376326 2208161418665872,28614197357895055,372754395074051500,4878709294080115494,64123505084010848580,846018700129069313495
%N A376326 Expansion of (1/x) * Series_Reversion( x * (1-x-x^2)^4 ).
%H A376326 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A376326 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} binomial(4*n+k+3,k) * binomial(5*n-k+3,n-2*k).
%F A376326 G.f.: B(x)^4, where B(x) is the g.f. of A365188.
%o A376326 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*(1-x-x^2)^4)/x)
%o A376326 (PARI) a(n, s=2, t=4, u=0) = sum(k=0, n\s, binomial(t*(n+1)+k-1, k)*binomial((t+u+1)*(n+1)-(s-1)*k-2, n-s*k))/(n+1);
%Y A376326 Cf. A001002, A368961, A368963.
%Y A376326 Cf. A365188.
%K A376326 nonn
%O A376326 0,2
%A A376326 _Seiichi Manyama_, Sep 20 2024