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 A385983 #9 Jul 14 2025 10:03:35
%S A385983 1,1,4,46,1432,123808,30876832,22731703408,49898049707776,
%T A385983 327831911519538304,6455998409280026369536,
%U A385983 381291302353791118798096384,67549186687935750257213597283328,35899285521583612190120694413539704832,57235559192922896714567337515980987820597248
%N A385983 a(0) = 1; a(n) = Sum_{k=0..n-1} 3^k * binomial(n-1,k) * a(k) * a(n-1-k).
%F A385983 E.g.f. A(x) satisfies A'(x) = A(x) * A(3*x).
%o A385983 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, i-1, 3^j*binomial(i-1, j)*v[j+1]*v[i-j])); v;
%Y A385983 Cf. A000142, A126444, A155585, A385984.
%K A385983 nonn
%O A385983 0,3
%A A385983 _Seiichi Manyama_, Jul 14 2025