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 A339831 #9 Jan 09 2021 22:13:01
%S A339831 2,3,9,28,97,346,1302,5014,19830,79813,326344,1350918,5652334,
%T A339831 23861787,101519790,434827232,1873491739,8114411769,35309142309,
%U A339831 154288183928,676730773252,2978405318453,13149337960554,58218455727085,258435947527696,1149982662789042
%N A339831 Number of rooted bicolored trees on n nodes such that black nodes are not adjacent to each other.
%H A339831 Andrew Howroyd, <a href="/A339831/b339831.txt">Table of n, a(n) for n = 1..500</a>
%e A339831 a(1) = 2: B, W.
%e A339831 a(2) = 3: B(W), W(B), W(W).
%e A339831 a(3) = 9: B(WW), W(BB), W(BW), W(WW), B(W(B)), B(W(W)), W(B(W)), W(W(B)), W(W(W)).
%o A339831 (PARI) EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)}
%o A339831 seq(n)={my(u=v=[]); for(n=1, n, my(t=concat([1], EulerT(v))); v=concat([1], EulerT(u + v)); u=t); u + v}
%Y A339831 Cf. A038055 (rooted bicolored trees), A339830 (unrooted case), A339835, A339838.
%K A339831 nonn
%O A339831 1,1
%A A339831 _Andrew Howroyd_, Dec 19 2020