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 A383989 #17 May 27 2025 10:32:10
%S A383989 0,1,-11,61,-467,4381,-49091,643021,-9615827,161844541,-3026079971,
%T A383989 62243374381,-1396619164787,33949401567901,-888725861445251,
%U A383989 24926889744928141,-745755560487363347,23705772035082494461,-797875590555470224931,28346366547928396344301
%N A383989 Series expansion of the exponential generating function ff6^!(exp(x)-1) where ff6^!(x) = x * (1-3*x-x^2+x^3) / (1+3*x+x^2-x^3).
%H A383989 Michael De Vlieger, <a href="/A383989/b383989.txt">Table of n, a(n) for n = 0..407</a>
%H A383989 Bérénice Delcroix-Oger and Clément Dupont, <a href="https://arxiv.org/abs/2505.06094">Lie-operads and operadic modules from poset cohomology</a>, arXiv:2505.06094 [math.CO], 2025. See p. 28, Table 2, operad "FF6".
%t A383989 nn = 19; f[x_] := x*(1 - 3*x - x^2 + x^3)/(1 + 3*x + x^2 - x^3);
%t A383989 Range[0, nn]! * CoefficientList[Series[f[-(1 - Exp[x])], {x, 0, nn}], x]
%Y A383989 Cf. A002050, A006531, A084099, A101851, A114285, A225883, A383985, A383986, A383987, A383988, A383995.
%K A383989 sign,easy
%O A383989 0,3
%A A383989 _Michael De Vlieger_, May 16 2025