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 A111557 #4 Mar 30 2012 18:36:50
%S A111557 1,5,34,282,2696,28792,337072,4273632,58195072,846038912,13072140032,
%T A111557 213897731712,3695682017792,67254929193472,1286282280266752,
%U A111557 25802708552696832,541894309127053312,11894387852938452992
%N A111557 Column 4 of triangle A111553; also found in column 0 of triangle A111560, which equals the matrix logarithm of A111553.
%F A111557 a(n) = A111553(n+4, 4) = A111560(n+1, 0).
%o A111557 (PARI) {a(n)=if(n<0,0,(matrix(n+5,n+5,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))))^-1)[n+5,5])}
%Y A111557 Cf. A111553, A111560.
%K A111557 nonn
%O A111557 0,2
%A A111557 _Paul D. Hanna_, Aug 07 2005