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 A369425 #5 Jan 23 2024 08:40:48
%S A369425 1,2,3,6,10,15,24,40,64,97,144,216,328,496,737,1074,1546,2218,3186,
%T A369425 4578,6555,9318,13130,18358,25530,35398,49002,67735,93416,128392,
%U A369425 175704,239352,324680,438888,591672,795993,1068984,1433032,1917128,2558648,3405784,4520872,5984872,7903256,10413561
%N A369425 Expansion of Sum_{n>=1} x^(n*(n+1)/2)*((1+x)/(1-x))^n.
%o A369425 (PARI) my(N=66,x='x+O('x^N)); Vec(sum(n=1,N,x^(n*(n+1)/2)*((1+x)/(1-x))^n))
%Y A369425 Cf. A369424.
%K A369425 nonn,easy
%O A369425 1,2
%A A369425 _Joerg Arndt_, Jan 23 2024