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 A306731 #5 Mar 06 2019 20:14:13
%S A306731 1,1,2,2,4,6,10,14,24,37,56,90,135,204,316,474,704,1068,1579,2332,
%T A306731 3445,5054,7376,10750,15587,22497,32437,46544,66520,94908,134912,
%U A306731 191185,270301,380924,535469,750898,1050268,1465284,2039741,2832694,3925036,5427381,7488315,10310431
%N A306731 Expansion of Sum_{k>=0} x^k * Product_{j=1..k} (1 + x^j)^j.
%t A306731 nmax = 43; CoefficientList[Series[Sum[x^k Product[(1 + x^j)^j, {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
%Y A306731 Cf. A000009, A206100, A306703.
%K A306731 nonn
%O A306731 0,3
%A A306731 _Ilya Gutkovskiy_, Mar 06 2019