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%I #8 Dec 08 2020 15:24:03
%S 1,2,8,22,69,194,564,1584,4484,12550,35204,98412,275422,770416,
%T 2157334,6044684,16956389,47614380,133865184,376789710,1061822884,
%U 2995785714,8461975888,23928712708,67739408492,191964821890,544559201634,1546306248630,4394984617389
%N Number of unlabeled rooted trees with n nodes rooted at two indistinguishable nodes at distance 3 from each other.
%C Number of unoriented linear forests with n nodes and 4 rooted trees.
%H Andrew Howroyd, <a href="/A339302/b339302.txt">Table of n, a(n) for n = 4..500</a>
%F G.f.: (r(x)^4 + r(x^2)^2)/2 where r(x) is the g.f. of A000081.
%Y Cf. A000081.
%Y Column 4 of A339303.
%K nonn
%O 4,2
%A _Andrew Howroyd_, Dec 04 2020
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