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 A144271 #6 Jul 01 2023 12:11:18
%S A144271 1,2,5,21,129,1099,11647,148292,2190302,36842892,694276152,
%T A144271 14488348603,331537914373,8254117606799,222087256536602,
%U A144271 6421589319659283,198565371839434761,6538245667687424041,228396692050813678534,8436237099236470594589
%N A144271 Row sums of triangle A144270 (called S2hat(-1)).
%F A144271 a(n) = Sum_{m=1..n} A144270(n,m), n>=1.
%Y A144271 Cf. A144270.
%K A144271 nonn,easy
%O A144271 1,2
%A A144271 _Wolfdieter Lang_, Oct 09 2008