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 A135882 #5 Mar 30 2012 18:37:07
%S A135882 1,2,7,34,215,1698,16220,182714,2378780,35219202,585245185,
%T A135882 10797322816,219163958124,4856832298391,116735215192864,
%U A135882 3025759884533190,84155831914971391,2500599947944218716,79072271422935678302
%N A135882 Column 1 of triangle A135880.
%H A135882 Paul D. Hanna, <a href="/A135882/b135882.txt">Table of n, a(n) for n = 0..79</a>
%e A135882 Equals column 1 of triangle P=A135880:
%e A135882 1;
%e A135882 1, 1;
%e A135882 2, 2, 1;
%e A135882 6, 7, 3, 1;
%e A135882 25, 34, 15, 4, 1;
%e A135882 138, 215, 99, 26, 5, 1;
%e A135882 970, 1698, 814, 216, 40, 6, 1; ...
%e A135882 where column k of P^2 equals column 0 of P^(2k+2)
%e A135882 such that column 0 of P^2 equals column 0 of P shift left.
%o A135882 (PARI) {a(n)=local(P=Mat(1),R,PShR);if(n==0,1,for(i=0,n, 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[n+2,2])}
%Y A135882 Cf. A135880; other columns: A135881, A135883, A135884.
%K A135882 nonn
%O A135882 0,2
%A A135882 _Paul D. Hanna_, Dec 15 2007
%E A135882 Error in entries (false comma) corrected by _N. J. A. Sloane_, Jan 23 2008