A137512 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.

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, 15, 15, 16

Offset

1,3

Links

Table of n, a(n) for n=1..31.

Example

For n=12:
.....0..
.....00.
...0.000
..00000.
we can see nodes 7,8,9,10,11,12 ==> a(12) = 6

Crossrefs

Sequence in context: A340068 A196369 A245710 * A157943 A267098 A304110

Adjacent sequences: A137509 A137510 A137511 * A137513 A137514 A137515

Keyword

nonn

Author

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

Extensions

I think I managed to destroy the example by editing it. - N. J. A. Sloane, May 16 2008

Status

approved