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 A225800 #17 Jul 06 2024 21:27:03
%S A225800 1,1,1,1,1,1,1,1,1,1,3,2,1,1,5,4,1,1,7,6,1,1,1,9,8,6,3,1,1,11,10,15,
%T A225800 10,1,1,13,12,28,21,1,1,1,15,14,45,36,10,4,1,1,17,16,66,55,35,20,1,1,
%U A225800 19,18,91,78,84,56,1,1,1,21,20,120,105,165,120,15,5,1
%N A225800 Triangle of rising diagonals of A011973 (with rows displayed as centered text).
%C A225800 Row sums are A227300.
%F A225800 r(n) = binomial(2n-k-2-3*floor(k/2), floor(k/2)), k = 0..floor((2n-1)/3). - _John Molokach_, Jul 29 2013
%e A225800 Triangle begins:
%e A225800 1;
%e A225800 1, 1;
%e A225800 1, 1;
%e A225800 1, 1, 1;
%e A225800 1, 1, 3, 2;
%e A225800 1, 1, 5, 4;
%e A225800 1, 1, 7, 6, 1;
%e A225800 1, 1, 9, 8, 6, 3;
%e A225800 1, 1, 11, 10, 15, 10;
%e A225800 1, 1, 13, 12, 28, 21, 1;
%t A225800 Table[Binomial[2 n - k - 2 - 3 Floor[k/2], Floor[k/2]], {n, 1, 25}, {k, 0, Floor[(2 n - 1)/3]}] (* _John Molokach_, Jul 29 2013 *)
%Y A225800 Cf. A011973, A000045, A227300, A005314, A224838.
%K A225800 nonn,tabf
%O A225800 1,11
%A A225800 _John Molokach_, Jul 27 2013