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 A385877 #7 Jul 11 2025 08:49:17
%S A385877 1,1,2,14,309,17637,2240632,566921596,262489646519,208155482551991,
%T A385877 268104800528280951,537014337938584568385,1613191612128443060280697,
%U A385877 7048035233444754041436840277,43620293298146615746333469478901,373782307403691698916363133787269075
%N A385877 a(n) = 1 + Sum_{k=0..n-1} binomial(k+4,5) * a(k) * a(n-1-k).
%F A385877 G.f. A(x) satisfies A(x) = 1/( (1 - x) * ( 1 - x*Sum_{k=1..5} binomial(4,k-1) * x^k/k! * (d^k/dx^k A(x)) ) ).
%o A385877 (PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=1+sum(j=0, i-1, binomial(j+4, 5)*v[j+1]*v[i-j])); v;
%Y A385877 Cf. A143917, A385874, A385875, A385876.
%Y A385877 Cf. A385843.
%K A385877 nonn
%O A385877 0,3
%A A385877 _Seiichi Manyama_, Jul 11 2025