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 A386454 #8 Jul 22 2025 09:51:31
%S A386454 1,1,2,13,220,8148,586948,75141039,15930666825,5289069956220,
%T A386454 2628685323745449,1884772989271329869,1890430039448133854031,
%U A386454 2584219798288871040676608,4708450397910844142927823544,11215531466814325127916787062534,34341962107081618846057340207455738
%N A386454 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} binomial(k+3,4) * a(k) * a(n-1-k).
%F A386454 G.f. A(x) satisfies A(x) = 1/( 1 - x - x*Sum_{k=1..4} binomial(3,k-1) * x^k/k! * (d^k/dx^k A(x)) ).
%o A386454 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, binomial(j+3, 4)*v[j+1]*v[i-j])); v;
%Y A386454 Cf. A075834, A386452, A386453, A386455.
%Y A386454 Cf. A385876.
%K A386454 nonn
%O A386454 0,3
%A A386454 _Seiichi Manyama_, Jul 22 2025