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 A293571 #15 Jul 28 2020 02:59:12
%S A293571 1,1,-1,-5,25,41,-1049,2899,54545,-610415,-1363409,92652011,
%T A293571 -651996311,-10663181255,262674487895,-529402905149,-68312606260319,
%U A293571 1136414207246369,7701376416944095,-584076369474366245,6461047290787787321,173442620419212050761
%N A293571 E.g.f.: exp(x/(1 + x + x^2)).
%H A293571 Robert Israel, <a href="/A293571/b293571.txt">Table of n, a(n) for n = 0..446</a>
%H A293571 Robert Israel, <a href="/A293571/a293571.png">Plot of a(n)/(n! exp(sqrt(n))) for n = 2 .. 2500</a>
%F A293571 E.g.f.: Product_{k>0} exp(x^(3*k-2)) / exp(x^(3*k-1)).
%F A293571 a(n) = (3-2*n)*a(n-1) - 3*(n-2)*(n-1)*a(n-2) + (5-2*n)*(n-1)*(n-2)*a(n-3) - (n-4)*(n-3)*(n-2)*(n-1)*a(n-4). - _Robert Israel_, Jul 27 2020
%p A293571 f:= gfun:-rectoproc({a(n) = (3-2*n)*a(n-1) - 3*(n-2)*(n-1)*a(n-2) + (5-2*n)*(n-1)*(n-2)*a(n-3)- (n-4)*(n-3)*(n-2)*(n-1)*a(n-4),a(0)=1,a(1)=1,a(2)=-1,a(3)=-5},a(n),remember):
%p A293571 map(f, [$0..30]); # _Robert Israel_, Jul 27 2020
%o A293571 (PARI) N=66; x='x+O('x^N); Vec(serlaplace(exp(x/(1+x+x^2))))
%o A293571 (PARI) N=66; x='x+O('x^N); Vec(serlaplace(prod(k=1, N, exp(x^(3*k-2)-x^(3*k-1)))))
%Y A293571 Cf. A111884, A293572, A293573.
%K A293571 sign
%O A293571 0,4
%A A293571 _Seiichi Manyama_, Oct 12 2017