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 A365539 #14 Sep 09 2023 11:24:12
%S A365539 1,4,1,9,2,1,16,5,2,1,25,8,3,2,1,36,13,6,3,2,1,49,18,9,4,3,2,1,64,25,
%T A365539 12,7,4,3,2,1,81,32,17,10,5,4,3,2,1,100,41,22,13,8,5,4,3,2,1,121,50,
%U A365539 27,16,11,6,5,4,3,2,1,144,61,34,21,14,9,6,5,4,3,2,1
%N A365539 Array read by ascending antidiagonals: A(n,k) = [x^n] (1 + x^k)/((1 - x)^2*(1 - x^k)), with k > 0.
%e A365539 Array begins:
%e A365539 1, 1, 1, 1, 1, 1, 1, ...
%e A365539 4, 2, 2, 2, 2, 2, 2, ...
%e A365539 9, 5, 3, 3, 3, 3, 3, ...
%e A365539 16, 8, 6, 4, 4, 4, 4, ...
%e A365539 25, 13, 9, 7, 5, 5, 5, ...
%e A365539 36, 18, 12, 10, 8, 6, 6, ...
%e A365539 49, 25, 17, 13, 11, 9, 7, ...
%e A365539 64, 32, 22, 16, 14, 12, 10, ...
%e A365539 ...
%t A365539 A[n_,k_]:=SeriesCoefficient[(1+x^k)/((1-x)^2*(1-x^k)),{x,0,n}]; Table[A[n-k,k],{n,0,12},{k,n}]//Flatten
%Y A365539 Cf. A000027 (main diagonal and superdiagonals), A000290 (k=1), A000982 (k=2), A008810 (k=3), A008811 (k=4), A008812 (k=5), A008813 (k=6), A008814 (k=7), A008815 (k=8), A008816 (k=9), A008817 (k=10).
%Y A365539 Cf. A365540 (antidiagonal sums).
%K A365539 nonn,tabl
%O A365539 0,2
%A A365539 _Stefano Spezia_, Sep 08 2023