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 A111561 #3 Mar 30 2012 18:36:50
%S A111561 0,2,7,44,354,3328,35144,407984,5137824,69566144,1006372864,
%T A111561 15481560064,252326173824,4344015683584,78793242566144,
%U A111561 1502374856981504,30052439647908864,629485600310349824,13783057303819485184
%N A111561 Column 1 of A111560, which is the matrix log of A111553.
%o A111561 (PARI) {a(n)=local(M=matrix(n+2,n+2,m,j,if(m==j,1,if(m==j+1,-m+1, -(m-j-1)*polcoeff(log(sum(i=0,m,(i+3)!/3!*x^i)),m-j-1))))); if(n<0,0,sum(i=1,#M,(M^0-M)^i/i)[n+2,2])}
%Y A111561 Cf. A111560, A111553.
%K A111561 nonn
%O A111561 0,2
%A A111561 _Paul D. Hanna_, Aug 07 2005