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 A307680 #6 Apr 22 2019 18:06:30
%S A307680 1,1,3,17,131,1239,14029,187627,2906553,50982929,993806531,
%T A307680 21270277401,496425262123,12577053063847,344382608381421,
%U A307680 10139294386051139,319175215666010609,10684742192933940897,378662321114852778883,14158327369578651838369,557151639159864934384851
%N A307680 Expansion of e.g.f. Product_{k>=1} (1 + x^k/(1 - x)^k)^(1/k).
%F A307680 E.g.f.: exp(Sum_{k>=1} A048272(k)*x^k/(k*(1 - x)^k)).
%F A307680 a(n) = Sum_{k=0..n} binomial(n-1,k-1)*A168243(k)*n!/k!.
%e A307680 E.g.f.: A(x) = 1 + x + 3*x^2/2! + 17*x^3/3! + 131*x^4/4! + 1239*x^5/5! + 14029*x^6/6! + 187627*x^7/7! + 2906553*x^8/8! + ...
%t A307680 nmax = 20; CoefficientList[Series[Product[(1 + x^k/(1 - x)^k)^(1/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
%t A307680 nmax = 20; CoefficientList[Series[Exp[Sum[Sum[(-1)^(d + 1), {d, Divisors[k]}] x^k/(k (1 - x)^k), {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
%Y A307680 Cf. A048272, A129519, A168243, A307679, A320564.
%K A307680 nonn
%O A307680 0,3
%A A307680 _Ilya Gutkovskiy_, Apr 21 2019