OFFSET
1,3
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
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 03 2004
STATUS
approved