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 A370281 #8 Feb 14 2024 10:48:16
%S A370281 1,2,10,59,370,2392,15757,105156,708546,4809695,32841380,225321967,
%T A370281 1552063981,10726766624,74348039020,516586596484,3597106344450,
%U A370281 25095046641861,175369603836301,1227366066102925,8601637753421020,60355768595163030,423972992316330225
%N A370281 Coefficient of x^n in the expansion of 1/( (1-x)^2 - x^3 )^n.
%F A370281 a(n) = Sum_{k=0..floor(n/3)} binomial(n+k-1,k) * binomial(3*n-k-1,n-3*k).
%F A370281 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 - x^3) ). See A369214.
%o A370281 (PARI) a(n) = sum(k=0, n\3, binomial(n+k-1, k)*binomial(3*n-k-1, n-3*k));
%Y A370281 Cf. A369214.
%K A370281 nonn
%O A370281 0,2
%A A370281 _Seiichi Manyama_, Feb 13 2024