|
Search: id:A111299
|
|
|
| A111299 |
|
Numbers n such that the Matula tree of n is a binary tree (i.e. all nodes except root and leaves have degree 3). |
|
+0
1
|
|
| 4, 14, 49, 86, 301, 454, 886, 1589, 1849, 3101, 3986, 6418, 9761, 13766, 13951, 19049, 22463, 26798, 31754, 48181, 51529, 57026, 75266, 85699, 93793, 100561
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
REFERENCES
|
F. Goebel, On a 1-1-correspondence between rooted trees and natural numbers, J. Combin. Theory, B 29 (1980), 141-143. D. Matula, A natural rooted tree enumeration by prime factorization, SIAM Rev. 10 (1968).
|
|
LINKS
|
Keith Briggs, Matula numbers and rooted trees
|
|
FORMULA
|
The Matula tree of n is defined by as follows (p_m denotes the m-th prime):
matula(n):
... create a node labeled n
... for each prime factor m of n:
...... add the subtree matula(p_m), by an edge labeled m
... return the node
|
|
CROSSREFS
|
Cf. A061773, A005517, A005518.
Sequence in context: A014325 A047028 A047138 this_sequence A110686 A071729 A071733
Adjacent sequences: A111296 A111297 A111298 this_sequence A111300 A111301 A111302
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Keith Briggs (keith.briggs(AT)bt.com), Nov 02 2005
|
|
|
Search completed in 0.002 seconds
|
