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 A365844 #10 Sep 20 2023 10:01:10
%S A365844 1,7,74,931,12894,189798,2913980,46140347,748022678,12354604274,
%T A365844 207148525484,3516699607022,60328735646620,1044182053141612,
%U A365844 18212018061261600,319771572646888811,5647677332549552870,100266714048150595770,1788366334642393259292
%N A365844 Expansion of (1/x) * Series_Reversion( x*(1-x)^4/(1+x)^3 ).
%F A365844 a(n) = (1/(n+1)) * Sum_{k=0..n} binomial(4*n+k+3,k) * binomial(3*(n+1),n-k).
%o A365844 (PARI) a(n) = sum(k=0, n, binomial(4*n+k+3, k)*binomial(3*(n+1), n-k))/(n+1);
%Y A365844 Cf. A007297, A365842, A365843, A365845.
%K A365844 nonn
%O A365844 0,2
%A A365844 _Seiichi Manyama_, Sep 20 2023