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 A306664 #5 Mar 04 2019 23:15:40 %S A306664 1,0,1,1,1,1,2,2,4,4,7,7,12,12,19,22,31,37,54,63,89,111,146,184,247, %T A306664 301,398,501,642,804,1042,1293,1663,2082,2648,3321,4229,5268,6691, %U A306664 8370,10553,13168,16595,20659,25929,32253,40321,50092,62489,77418,96340,119266,147998,182927,226609 %N A306664 Expansion of Sum_{k>=0} x^(k*(k+1)) / Product_{j=1..k} (1 - x^j)^j. %t A306664 nmax = 54; CoefficientList[Series[Sum[x^(k (k + 1))/Product[(1 - x^j)^j, {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x] %Y A306664 Cf. A003106, A206100, A206138. %K A306664 nonn %O A306664 0,7 %A A306664 _Ilya Gutkovskiy_, Mar 04 2019