A250308 Number of unlabeled unrooted trees on 2n vertices with all vertices of odd degree.

1, 1, 2, 3, 7, 13, 32, 74, 192, 497, 1379, 3844, 11111, 32500, 96977, 292600, 894353, 2758968, 8590147, 26947946, 85138589, 270646644, 865260519, 2780393959, 8976443582, 29104709339, 94741504408, 309529405055, 1014690513653, 3336805406462, 11005284876792

Offset

1,3

References

F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973, section 3.2.

Links

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

StackExchange, Trees with odd degree sequence.

Example

When n=2 we have four vertices in the tree and the path graph does not qualify, as it contains two nodes of degree two, but the star with a center node connected to three neighboring nodes qualifies (degrees three and one are both odd).

Crossrefs

Sequence in context: A032131 A324844 A007827 * A259145 A237255 A129859

Adjacent sequences: A250305 A250306 A250307 * A250309 A250310 A250311

Keyword

nonn

Author

Marko Riedel, Jan 15 2015

Status

approved