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 A372464 #6 May 02 2024 09:46:10
%S A372464 1,4,32,286,2688,26004,256334,2560352,25824768,262447684,2683152032,
%T A372464 27565067600,284330359950,2942808943572,30546407611136,
%U A372464 317867390671536,3314979452815360,34637849797078380,362544825234198020,3800439733237986800,39893311092729794688
%N A372464 Coefficient of x^n in the expansion of 1 / ( (1-x) * (1-x+x^2) )^(2*n).
%F A372464 a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(2*n+k-1,k) * binomial(5*n-k-1,n-2*k).
%F A372464 The g.f. exp( Sum_{k>=1} a(k) * x^k/k ) has integer coefficients and equals (1/x) * Series_Reversion( x * (1-x)^2 * (1-x+x^2)^2 ). See A368975.
%o A372464 (PARI) a(n, s=2, t=2, u=2) = sum(k=0, n\s, (-1)^k*binomial(t*n+k-1, k)*binomial((t+u+1)*n-(s-1)*k-1, n-s*k));
%Y A372464 Cf. A368975, A372460.
%K A372464 nonn
%O A372464 0,2
%A A372464 _Seiichi Manyama_, May 01 2024