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 A342797 #49 May 01 2021 22:12:03
%S A342797 1,1,5,4,1,5,15,15,9,1,5,15,34,36,29,16,1,5,15,34,65,70,63,47,25,1,5,
%T A342797 15,34,65,111,120,114,96,69,36,1,5,15,34,65,111,175,189,185,166,135,
%U A342797 95,49,1,5,15,34,65,111,175,260,280,279,260,226,180,125,64
%N A342797 Irregular triangle read by rows: T(n, k) is the k-th antidiagonal sum of the n X n matrices defined in A069480 and A078475.
%F A342797 T(n, k) = A006003(k) for 1 <= k <= n.
%F A342797 T(n, k) = (k^3 + 2*n - 6*k^2*n - 4*n^3 + k*(10*n^2 - 1))/2 for n < k <= 2*n - 1.
%F A342797 T(n, 2*n-1) = A000290(n).
%e A342797 The triangle T(n, k) begins:
%e A342797 1
%e A342797 1 5 4
%e A342797 1 5 15 15 9
%e A342797 1 5 15 34 36 29 16
%e A342797 1 5 15 34 65 70 63 47 25
%e A342797 ...
%t A342797 T[n_,k_]:=If[k<=n,(k+k^3)/2,(k^3+2n-6k^2n-4n^3+k(10n^2-1))/2]; Flatten[Table[T[n,k],{n,8},{k,2n-1}]]
%Y A342797 Cf. A000290 (diagonal), A006003, A037270 (row sums), A060747 (row length), A069480, A078475.
%K A342797 nonn,tabf
%O A342797 1,3
%A A342797 _Stefano Spezia_, Apr 25 2021