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 A144217 #8 Dec 21 2023 10:21:40
%S A144217 0,1,1,2,0,2,3,0,0,3,4,0,0,0,4,5,0,0,0,0,5,6,0,0,0,0,0,6,7,0,0,0,0,0,
%T A144217 0,7,8,0,0,0,0,0,0,0,8,9,0,0,0,0,0,0,0,0,9,10,0,0,0,0,0,0,0,0,0,10,11,
%U A144217 0,0,0,0,0,0,0,0,0,0,11,12,0,0,0,0,0,0,0,0,0,0,0,12,13,0,0,0,0,0,0,0,0,0,0
%N A144217 Weight array of A144216: a rectangular array by antidiagonals.
%H A144217 Paolo Xausa, <a href="/A144217/b144217.txt">Table of n, a(n) for n = 1..11325</a> (antidiagonals 1..150 of the array, flattened).
%F A144217 Start with R(m,n)=(m(m-1)+n(n-1))/2 for m>=1,n>=1. Put R(m,n)=0 if m=0 or n=0. Define w(m,n)=R(m,n)-R(m-1,n-1)-R(m,n-1)-R(m-1,n) for m>=1, n>=1. Then the weight array W={w(m,n)} is A144217. (See A144112.)
%e A144217 Northwest corner:
%e A144217 0 1 2 3 4 5
%e A144217 1 0 0 0 0 0
%e A144217 2 0 0 0 0 0
%e A144217 3 0 0 0 0 0
%e A144217 4 0 0 0 0 0
%t A144217 Array[Append[PadRight[{#},#,0],#]&,15,0] (* _Paolo Xausa_, Dec 21 2023 *)
%Y A144217 Cf. A144217.
%K A144217 nonn,tabl
%O A144217 1,4
%A A144217 _Clark Kimberling_, Sep 14 2008