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 A135886 #2 Mar 30 2012 18:37:07
%S A135886 1,4,20,126,980,9186,101492,1296934,18868652,308478492,5605768476,
%T A135886 112198139500,2454071216496,58267971181456,1493114371576942,
%U A135886 41084194594171729,1208473333806735096,37849717704435895370
%N A135886 Column 1 of triangle Q = A135885; also equals column 0 of Q^2.
%e A135886 Triangle Q = A135885 begins:
%e A135886 1;
%e A135886 2, 1;
%e A135886 6, 4, 1;
%e A135886 25, 20, 6, 1;
%e A135886 138, 126, 42, 8, 1;
%e A135886 970, 980, 351, 72, 10, 1;
%e A135886 8390, 9186, 3470, 748, 110, 12, 1; ...
%e A135886 where column k of Q equals column 0 of Q^(k+1) such that
%e A135886 column 0 of Q equals column 0 of P=A135880 shift left and Q=P^2.
%o A135886 (PARI) {a(n)=local(P=Mat(1),R,PShR);if(n==0,1,for(i=0,n+1, PShR=matrix(#P,#P, r,c, if(r>=c,if(r==c,1,if(c==1,0,P[r-1,c-1]))));R=P*PShR; R=matrix(#P+1, #P+1, r,c, if(r>=c, if(r<#P+1,R[r,c], if(c==1,(P^2)[ #P,1],(P^(2*c-1))[r-c+1,1])))); P=matrix(#R, #R, r,c, if(r>=c, if(r<#R,P[r,c], (R^c)[r-c+1,1]))));(P^2)[n+2,2])}
%Y A135886 Cf. A135885; other columns: A135881, A135887.
%K A135886 nonn
%O A135886 0,2
%A A135886 _Paul D. Hanna_, Dec 15 2007