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 A105624 #3 Mar 30 2012 18:36:45
%S A105624 1,3,19,167,1831,23843,358339,6097607,115840951,2430329603,
%T A105624 55812650419,1392737182247,37528377195271,1086086115808163,
%U A105624 33600297897404899,1106632150406054087,38659524289511283991,1427864216163041265923
%N A105624 Column 2 of triangle A105623.
%C A105624 A105623 equals the matrix square-root of triangle A105615.
%o A105624 (PARI) {a(n)=local(R,M=matrix(n+3,n+3,m,j,if(m>=j,if(m==j,1,if(m==j+1,-2*j, polcoeff(1/sum(i=0,m-j,(2*i)!/i!/2^i*x^i)+O(x^m),m-j)))))^-1); R=(M+M^0)/2;for(i=1,floor(2*log(n+2)),R=(R+M*R^(-1))/2); return(if(n<0,0,R[n+3,3]))}
%Y A105624 Cf. A105615, A105623.
%K A105624 nonn
%O A105624 0,2
%A A105624 _Paul D. Hanna_, Apr 16 2005