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 A381913 #13 Mar 10 2025 09:42:50
%S A381913 1,4,28,245,2422,25860,291106,3405405,41014131,505344113,6341182427,
%T A381913 80768735045,1041645452650,13575670575944,178528253213469,
%U A381913 2366073408348545,31571528771106126,423794981085407622,5718929869862880055,77539914280883389432,1055790501909183080512
%N A381913 Expansion of (1/x) * Series_Reversion( x * (1-x)^3 / B(x) ), where B(x) is the g.f. of A001764.
%F A381913 G.f. A(x) satisfies A(x) = B(x*A(x)) / (1 - x*A(x))^3.
%F A381913 a(n) = Sum_{k=0..n} binomial(n+3*k+1,k) * binomial(4*n-k+2,n-k)/(n+3*k+1).
%o A381913 (PARI) a(n) = sum(k=0, n, binomial(n+3*k+1, k)*binomial(4*n-k+2, n-k)/(n+3*k+1));
%Y A381913 Cf. A381911, A381912.
%Y A381913 Cf. A381880, A381916.
%Y A381913 Cf. A001764.
%K A381913 nonn
%O A381913 0,2
%A A381913 _Seiichi Manyama_, Mar 10 2025