A058889 Arrange binary trees in natural sequential order (see examples); sequence gives numbers of nodes.

1, 2, 3, 3, 4, 4, 4, 5, 5, 6, 4, 4, 5, 5, 6, 6, 6, 5, 5, 6, 6, 7, 7, 7, 7, 8, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 7, 7, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11

Offset

1,2

Links

Table of n, a(n) for n=1..99.

Example

The trees are x, (x,x), (x,(x,x)), ((x,x),x), ((x,x),(x,x)), (x,(x,(x,x))), ((x,(x,x)),x), ((x,x),(x,(x,x))), ((x,(x,x)),(x,x)), ((x,(x,x)),(x,(x,x))) (x,((x,x),x)), (((x,x),x),x), ((x,x)((x,x),x)), (((x,x),x),(x,x)), ((x,(xx)), ((x,x),x)),...

Crossrefs

Cf. A000108.

Sequence in context: A156077 A189641 A189672 * A226143 A166724 A110862

Adjacent sequences: A058886 A058887 A058888 * A058890 A058891 A058892

Keyword

nonn,nice,easy

Author

Claude Lenormand (claude.lenormand(AT)free.fr), Jan 08 2001

Extensions

More terms from John W. Layman, Feb 03 2003

Status

approved