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 A380748 #4 Feb 03 2025 21:26:20
%S A380748 1,0,2,5,15,50,180,695,2869,12616,58862,290305,1508483,8233942,
%T A380748 47086560,281420499,1753994617,11377449948,76667702218,535802458029,
%U A380748 3877528409495,29016786672794,224243915547756,1787491551588239,14680196745177309,124088256248966864,1078492866534953734
%N A380748 Antidiagonal sums of A380747.
%t A380748 A380747[0, 0]:=1; A380747[1, 0]:=-1; A380747[n_, k_]:=((k-1)*n+k)k^(n-1); a[n_]:=Sum[A[n-k,k],{k,0,n}]; Array[a,27,0]
%Y A380748 Cf. A380747.
%K A380748 nonn
%O A380748 0,3
%A A380748 _Stefano Spezia_, Jan 31 2025