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 A307665 #15 May 13 2021 02:35:15
%S A307665 1,1,3,1,2,11,1,2,7,42,1,2,6,26,163,1,2,6,21,99,638,1,2,6,20,78,382,
%T A307665 2510,1,2,6,20,71,297,1486,9908,1,2,6,20,70,262,1145,5812,39203,1,2,6,
%U A307665 20,70,253,990,4447,22819,155382,1,2,6,20,70,252,936,3796,17358,89846,616666
%N A307665 A(n,k) = Sum_{j=0..floor(n/k)} binomial(2*n,k*j+n), square array A(n,k) read by antidiagonals, for n >= 0, k >= 1.
%e A307665 Square array begins:
%e A307665 1, 1, 1, 1, 1, 1, 1, 1, ...
%e A307665 3, 2, 2, 2, 2, 2, 2, 2, ...
%e A307665 11, 7, 6, 6, 6, 6, 6, 6, ...
%e A307665 42, 26, 21, 20, 20, 20, 20, 20, ...
%e A307665 163, 99, 78, 71, 70, 70, 70, 70, ...
%e A307665 638, 382, 297, 262, 253, 252, 252, 252, ...
%e A307665 2510, 1486, 1145, 990, 936, 925, 924, 924, ...
%e A307665 9908, 5812, 4447, 3796, 3523, 3446, 3433, 3432, ...
%t A307665 T[n_, k_] := Sum[Binomial[2*n, k*j + n], {j, 0, Floor[n/k]}]; Table[T[n - k, k], {n, 0, 11}, {k, n, 1, -1}] // Flatten (* _Amiram Eldar_, May 13 2021*)
%Y A307665 Columns 1-2 give A032443, A114121.
%Y A307665 Cf. A306846, A306915, A307393, A307668.
%K A307665 nonn,tabl
%O A307665 0,3
%A A307665 _Seiichi Manyama_, Apr 20 2019