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 A119828 #7 Sep 23 2024 14:12:45
%S A119828 1,2,1,24,12,1,720,360,30,1,40320,20160,1680,56,1,3628800,1814400,
%T A119828 151200,5040,90,1,479001600,239500800,19958400,665280,11880,132,1,
%U A119828 87178291200,43589145600,3632428800,121080960,2162160,24024,182,1
%N A119828 Number triangle T(n,k)=(2n)!/(2k)!.
%C A119828 Row sums are A051396(n+1). Diagonal sums are A119829. Inverse is the bi-diagonal array A119830. E.g.f. cosh(x*y)/(1-y*x^2) produces an aerated version.
%F A119828 Number triangle T(n,k)=[k<=n](2n)!/(2k)!
%e A119828 Triangle begins as:
%e A119828 1,
%e A119828 2, 1,
%e A119828 24, 12, 1,
%e A119828 720, 360, 30, 1,
%e A119828 40320, 20160, 1680, 56, 1,
%e A119828 3628800, 1814400, 151200, 5040, 90, 1
%t A119828 Flatten[Table[(2n)!/(2k)!, {n, 0, 7}, {k, 0, n}]] (* _James C. McMahon_, Sep 23 2024 *)
%K A119828 easy,nonn,tabl
%O A119828 0,2
%A A119828 _Paul Barry_, May 25 2006