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The number of nodes visible from underneath a binary tree, where the nodes are placed such that the innermost of the two sprouting nodes should be underneath the mother.
0

%I #3 Mar 30 2012 16:50:48

%S 1,1,2,3,3,3,4,5,5,6,6,6,7,7,8,9,9,10,10,11,11,12,12,12,13,13,14,14,

%T 15,15,16

%N The number of nodes visible from underneath a binary tree, where the nodes are placed such that the innermost of the two sprouting nodes should be underneath the mother.

%e For n=12:

%e .....0..

%e .....00.

%e ...0.000

%e ..00000.

%e we can see nodes 7,8,9,10,11,12 ==> a(12) = 6

%K nonn

%O 1,3

%A David Reiss (david.reiss(AT)utoronto.ca), May 11 2008

%E I think I managed to destroy the example by editing it. - _N. J. A. Sloane_, May 16 2008