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 A166893 #2 Mar 30 2012 18:37:18
%S A166893 1,6,63,986,20685,545736,17365336,647216568,27653205177,1332422277828,
%T A166893 71470510481961,4223498675806638,272615162534575302,
%U A166893 19082609490868539738,1439738711122827542742,116468234559061615308870
%N A166893 Column 3 of triangle A166890.
%C A166893 Triangle A166890 transforms diagonals in the triangle A166888 of coefficients in the successive iterations of x*(1+x)^2.
%o A166893 (PARI) {a(n)=local(F=x, M, N, P, m=n+2); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x+2*x^2+x^3+x*O(x^(m+2)))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, M[r, c]); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+2, 3]}
%Y A166893 Cf. A166890, A166891, A166892.
%K A166893 nonn
%O A166893 1,2
%A A166893 _Paul D. Hanna_, Nov 22 2009