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 A102812 #11 Jan 27 2020 01:10:22
%S A102812 1,1,2,6,25,136,927,7690,75913,876026,11649009,176389234,3011057742,
%T A102812 57453864447,1216376055329,28390144638804,726364328468535,
%U A102812 20269424489285300,614148655197018345,20123000681064168210,710410428812211243412,26932611130467463342807
%N A102812 a(0) = 1, a(n) = Sum_{k=1..n} A001263(n,k)*a(k-1) where A001263(n,k) are Narayana numbers.
%C A102812 Eigensequence of A001263. - _Philippe Deléham_, Jun 22 2007
%H A102812 Andrew Howroyd, <a href="/A102812/b102812.txt">Table of n, a(n) for n = 0..200</a>
%o A102812 (PARI) \\ here T(n,k) is A001263.
%o A102812 T(n, k) ={if(k==0, 0, binomial(n-1, k-1) * binomial(n, k-1) / k)}
%o A102812 seq(n)={my(a=vector(n+1)); a[1]=1; for(n=1, n, a[n+1]=sum(k=1, n, a[k]*T(n,k))); a} \\ _Andrew Howroyd_, Nov 06 2019
%Y A102812 Cf. A001263.
%K A102812 nonn
%O A102812 0,3
%A A102812 _Gerald McGarvey_, Feb 26 2005
%E A102812 Terms a(12) and beyond from _Andrew Howroyd_, Nov 06 2019