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 A171844 #6 Apr 14 2021 05:23:36
%S A171844 1,4,12,31,77,188,462,1148,2887,7335,18789,48419,125321,325381,846713,
%T A171844 2206891,5758797,15040102,39304237,102760572,268757551,703079117,
%U A171844 1839625401,4814107671,12599351527,32977310272,86319400527,225954695164,591492569038,1548419254590
%N A171844 Row sums of triangle A171843.
%H A171844 Andrew Howroyd, <a href="/A171844/b171844.txt">Table of n, a(n) for n = 1..1000</a>
%F A171844 G.f.: Sum_{k>=1} x^k*(1 - x^k)/((1 - x)*(1 - 2*x + x^2 - x^k)). - _Andrew Howroyd_, Apr 13 2021
%e A171844 a(4) = 31 = (1 + 3 + 6 + 21) since row 4 of triangle A171843 = (1, 3, 6, 21).
%o A171844 (PARI) seq(n)={Vec(sum(k=1, n, x^k*(1 - x^k)/((1 - x)*(1 - 2*x + x^2 - x^k)) + O(x*x^n)))} \\ _Andrew Howroyd_, Apr 13 2021
%Y A171844 Cf. A171843.
%K A171844 nonn
%O A171844 1,2
%A A171844 _Gary W. Adamson_, Dec 19 2009
%E A171844 a(10) and a(13) corrected and a(14) and beyond from _Andrew Howroyd_, Apr 13 2021