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 A181146 #2 Mar 30 2012 18:37:22
%S A181146 1,4,27,236,2380,26216,306495,3740572,47159772,609924536,8051939324,
%T A181146 108110654120,1472276038688,20292738170064,282614171731527,
%U A181146 3971576995998588,56256063139701916,802448704561822616
%N A181146 Main diagonal of triangle A181145.
%C A181146 Triangle A181145 is formed from the coefficients of the g.f.:
%C A181146 * exp( Sum_{n>=1} [Sum_{k=0..2n} C(2n,k)^2*y^k]*x^n/n ).
%e A181146 Triangle A181145 begins:
%e A181146 (1);
%e A181146 1,(4), 1;
%e A181146 1, 12,(27), 12, 1;
%e A181146 1, 24, 134,(236), 134, 24, 1;
%e A181146 1, 40, 410, 1540,(2380), 1540, 410, 40, 1;
%e A181146 1, 60, 975, 6260, 18386,(26216), 18386, 6260, 975, 60, 1; ...
%e A181146 in which this sequence equals the central terms of the rows.
%o A181146 (PARI) {a(n)=polcoeff(polcoeff(exp(sum(m=1,n,sum(j=0,2*m,binomial(2*m,j)^2*y^j)*x^m/m)+O(x^(n+1))),n,x),n,y)}
%Y A181146 Cf. A181146.
%K A181146 nonn
%O A181146 0,2
%A A181146 _Paul D. Hanna_, Oct 16 2010