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%I #18 Nov 02 2014 19:57:25
%S 1,2,4,24,256,4000,82944,2151296,67108864,2448880128,102400000000,
%T 4829076871168,253613523861504,14681377947951104,928873060356849664,
%U 63772920000000000000,4722366482869645213696,375183514207494575620096
%N Number of labeled trees with 2-colored nodes.
%H Robert Israel, <a href="/A038058/b038058.txt">Table of n, a(n) for n = 0..321</a>
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%F a(n) = A038057(n)/n = 2^n * n^(n-2) for n>=1. E.g.f. B(2*x) where B(x) is e.g.f. of A000272.
%p 1, seq(2^n * n^(n-2), n=1..20); # _Robert Israel_, Nov 02 2014
%t nn = 17; f[x_] := Sum[n^(n - 2) x^n/n!, {n, 1, nn}];
%t Range[0, nn]! CoefficientList[Series[f[2 x] + 1, {x, 0, nn}], x] (* _Geoffrey Critzer_, Nov 02 2014 *)
%Y Cf. A000272, A038055-A038062.
%K nonn
%O 0,2
%A _Christian G. Bower_, Jan 04 1999
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