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 A370273 #8 Feb 14 2024 10:48:32
%S A370273 1,2,10,59,362,2277,14581,94572,619242,4084538,27099435,180651913,
%T A370273 1209036725,8118629365,54671662692,369071775684,2496852123882,
%U A370273 16923762715911,114902801532622,781296976824693,5319705042364587,36265061394634215,247497082392976415
%N A370273 Coefficient of x^n in the expansion of 1/( (1-x)^2 * (1-x^3) )^n.
%F A370273 a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,k) * binomial(3*n-3*k-1,n-3*k).
%F A370273 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) ). See A369297.
%o A370273 (PARI) a(n, s=3, t=1, u=2) = sum(k=0, n\s, binomial(t*n+k-1, k)*binomial((u+1)*n-s*k-1, n-s*k));
%Y A370273 Cf. A369297.
%K A370273 nonn
%O A370273 0,2
%A A370273 _Seiichi Manyama_, Feb 13 2024