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 A369214 #7 Jan 16 2024 08:32:51
%S A369214 1,2,7,31,155,833,4696,27393,163944,1001022,6211049,39048685,
%T A369214 248213672,1592561156,10300192220,67083304750,439571860881,
%U A369214 2895898913453,19169805142929,127442939722175,850536450459795,5696270624620125,38271171118343550
%N A369214 Expansion of (1/x) * Series_Reversion( x * ((1-x)^2-x^3) ).
%H A369214 <a href="/index/Res#revert">Index entries for reversions of series</a>
%F A369214 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(n+k,k) * binomial(3*n-k+1,n-3*k).
%o A369214 (PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x*((1-x)^2-x^3))/x)
%o A369214 (PARI) a(n) = sum(k=0, n\3, binomial(n+k, k)*binomial(3*n-k+1, n-3*k))/(n+1);
%Y A369214 Cf. A151374, A249924, A369160.
%Y A369214 Cf. A049140, A369114.
%K A369214 nonn
%O A369214 0,2
%A A369214 _Seiichi Manyama_, Jan 16 2024