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 A105618 #3 Mar 30 2012 18:36:45
%S A105618 1,3,15,107,991,11203,148879,2270027,39041151,747704963,15784630159,
%T A105618 364256650027,9124264794271,246600188525123,7153677209063439,
%U A105618 221729176945261067,7313478624348963391,255786689421734222083
%N A105618 Row sums of triangle A105615.
%o A105618 (PARI) {a(n)=if(n<0,0,sum(k=0,n,(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)[n+1,k+1]))}
%Y A105618 Cf. A105615.
%K A105618 nonn
%O A105618 0,2
%A A105618 _Paul D. Hanna_, Apr 16 2005