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 A105630 #3 Mar 30 2012 18:36:45
%S A105630 0,1,3,17,135,1353,16251,226857,3605775,64288209,1270969971,
%T A105630 27603549057,653517822615,16755529944729,462601460800491,
%U A105630 13685474246611737,431948067953729055,14489465807596684449,514794897939436455651
%N A105630 Column 0 of triangle A105629, which is the matrix logarithm of triangle A105623.
%C A105630 A105623 equals the matrix square-root of triangle A105615.
%o A105630 (PARI) {a(n)=local(L,M=matrix(n+1,n+1,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); L=sum(i=1,#M,(-1)^(i-1)*(M-M^0)^i/i); return(if(n<0,0,L[n+1,1]/2))}
%Y A105630 Cf. A105629, A105623, A105615.
%K A105630 nonn
%O A105630 0,3
%A A105630 _Paul D. Hanna_, Apr 16 2005