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 A119830 #2 Mar 30 2012 18:59:15 %S A119830 1,-2,1,0,-12,1,0,0,-30,1,0,0,0,-56,1,0,0,0,0,-90,1,0,0,0,0,0,-132,1, %T A119830 0,0,0,0,0,0,-182,1,0,0,0,0,0,0,0,-240,1,0,0,0,0,0,0,0,0,-306,1,0,0,0, %U A119830 0,0,0,0,0,0,-380,1,0,0,0,0,0,0,0,0,0,0,-462,1,0,0,0,0,0,0,0,0,0,0,0,-552,1,0,0,0,0,0,0 %N A119830 Bi-diagonal inverse of (2n)!/(2k)!. %C A119830 Row sums are 1-2n(n-1)=1-b(n). Inverse of A119828. %F A119830 Column k has g.f. x^k(1-b(k+1)x) where b(n)=2n(2n-1). %e A119830 Triangle begins %e A119830 1, %e A119830 -2, 1, %e A119830 0, -12, 1, %e A119830 0, 0, -30, 1, %e A119830 0, 0, 0, -56, 1, %e A119830 0, 0, 0, 0, -90, 1, %e A119830 0, 0, 0, 0, 0, -132, 1, %e A119830 0, 0, 0, 0, 0, 0, -182, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, -240, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, 0, -306, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, 0, 0, -380, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -462, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -552, 1, %e A119830 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -650, 1 %K A119830 easy,sign,tabl %O A119830 0,2 %A A119830 _Paul Barry_, May 25 2006