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 A305206 #4 May 27 2018 19:46:55 %S A305206 1,1,2,9,36,190,1070,6797,46942,350901,2806187,23894662,215598410, %T A305206 2053090936,20557071012,215697357449,2364810631734,27023086395647, %U A305206 321160376470277,3962047673946906,50648323260067319,669819485900273336,9150740338219903590,128965789655207156299 %N A305206 a(n) = [x^n] exp(Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 - x^k)^n)). %H A305206 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %F A305206 a(n) = [x^n] Product_{k>=1} (1 + x^k)^binomial(n+k-2,n-1). %t A305206 Table[SeriesCoefficient[Exp[Sum[(-1)^(k + 1) x^k/(k (1 - x^k)^n), {k, 1, n}]], {x, 0, n}], {n, 0, 23}] %t A305206 Table[SeriesCoefficient[Product[(1 + x^k)^Binomial[n + k - 2, n - 1], {k, 1, n}], {x, 0, n}], {n, 0, 23}] %Y A305206 Cf. A026007, A028377, A258343, A293554, A305205. %K A305206 nonn %O A305206 0,3 %A A305206 _Ilya Gutkovskiy_, May 27 2018