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 A378554 #14 Nov 30 2024 09:49:54
%S A378554 1,1,7,28,171,846,4942,26580,153363,856900,4939682,28140476,162676878,
%T A378554 936947116,5436375532,31526252208,183571246659,1069552636950,
%U A378554 6247183319938,36524006501180,213899020967786,1253905101529080,7359775341696180,43237184121401400
%N A378554 a(n) = Sum_{k=0..n} 4^(n-k) * binomial(n+k-1,k) * binomial(k/2,n-k).
%F A378554 a(n) = [x^n] 1/(1 - x*(1 + 4*x)^(1/2))^n.
%t A378554 a[n_]:=SeriesCoefficient[1/(1 - x*(1 + 4*x)^(1/2))^n,{x,0,n}]; Array[a,24,0] (* _Stefano Spezia_, Nov 30 2024 *)
%o A378554 (PARI) a(n) = sum(k=0, n, 4^(n-k)*binomial(n+k-1, k)*binomial(k/2, n-k));
%Y A378554 Cf. A213684, A378555.
%Y A378554 Cf. A372125.
%K A378554 nonn
%O A378554 0,3
%A A378554 _Seiichi Manyama_, Nov 30 2024