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 A293561 #7 Oct 12 2017 08:10:20
%S A293561 3,19,80,286,945,2997,9294,28456,86471,261559,788892,2375010,7141581,
%T A293561 21457705,64438874,193447948,580606275,1742343435,5228079240,
%U A293561 15686335270,47063200553,141197990749,423610749990,1270865804976,3812664524415,11438127791647
%N A293561 Column 3 of A142249.
%H A293561 Vaclav Kotesovec, <a href="/A293561/b293561.txt">Table of n, a(n) for n = 3..300</a>
%F A293561 a(n) ~ 3^n / 2.
%t A293561 Table[(CoefficientList[Simplify[(1-x)^n * PolyLog[-n, 2, x] / (x*Log[1-x])], x]/.x->1-E)[[3]], {n, 4, 20}]
%Y A293561 Cf. A142249.
%K A293561 nonn
%O A293561 3,1
%A A293561 _Vaclav Kotesovec_, Oct 12 2017