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 A370275 #9 Feb 14 2024 10:48:24
%S A370275 1,2,10,62,394,2552,16822,112310,756874,5137676,35076360,240606082,
%T A370275 1656906550,11447855850,79319081054,550925792312,3834743187594,
%U A370275 26742188401900,186802789016908,1306827910585782,9154542088193544,64206944261628146,450823141806229290
%N A370275 Coefficient of x^n in the expansion of 1/( (1-x)^2 * (1-x^3)^2 )^n.
%F A370275 a(n) = Sum_{k=0..floor(n/3)} binomial(2*n+k-1,k) * binomial(3*n-3*k-1,n-3*k).
%F A370275 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^3)^2 ). See A369298.
%o A370275 (PARI) a(n, s=3, t=2, u=2) = sum(k=0, n\s, binomial(t*n+k-1, k)*binomial((u+1)*n-s*k-1, n-s*k));
%Y A370275 Cf. A369298.
%K A370275 nonn
%O A370275 0,2
%A A370275 _Seiichi Manyama_, Feb 13 2024