help needed counting rooted trees
N. J. A. Sloane
njas at research.att.com
Wed Aug 31 00:08:54 CEST 2005
Take the standard rooted binary tree of depth n, with
2^(n+1) - 1 labeled nodes. Here is a poor picture of
the tree of depth 3.
o
/ \
/ \
o o
/ \ / \
o o o o
/ \ / \ / \ / \
o o o o o o o o
My question is, how many rooted subtrees are there?
(All rooted at the original root, of course.)
For n = 1 the 4 subtrees are:
o o o o
/ \ / \
o o o o
I get:
n: 0 1 2
#: 1 4 25
Is this A007830?
NJAS
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