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 A091488 #12 Aug 30 2018 18:56:44
%S A091488 1,1,1,3,6,16,42,115,319,909,2614,7622,22422,66556,198946,598617,
%T A091488 1811205,5508015,16825307,51605568,158860950,490666293,1520106655,
%U A091488 4722502437,14708971581,45921804883,143682973435,450477673623
%N A091488 Number of asymmetric rooted 2,3 cacti (triangular cacti with bridges).
%C A091488 Also asymmetric involution rooted trees.
%H A091488 Andrew Howroyd, <a href="/A091488/b091488.txt">Table of n, a(n) for n = 1..500</a>
%H A091488 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%H A091488 <a href="/index/Ca#cacti">Index entries for sequences related to cacti</a>
%H A091488 <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>
%F A091488 Shifts left under transform T where Ta = WEIGH(W_1, 2(a)). W_1, 2(a) has g.f. A(x)+(A(x^2)-A(x)^2)/2.
%o A091488 (PARI) WeighT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v,n,(-1)^(n-1)/n))))-1,-#v)}
%o A091488 seq(n)={my(p=O(x)); for(n=1, n, p=x+x^2*(Ser(WeighT(Vec(p + (p^2 - subst(p,x,x^2))/2))))); Vec(p)} \\ _Andrew Howroyd_, Aug 30 2018
%Y A091488 Cf. A091486, A091489.
%K A091488 nonn,eigen
%O A091488 1,4
%A A091488 _Christian G. Bower_, Jan 14 2004