OFFSET
0,4
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..127
E. M. Rains and N. J. A. Sloane, On Cayley's Enumeration of Alkanes (or 4-Valent Trees), J. Integer Sequences, Vol. 2 (1999), Article 99.1.1.
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
STATUS
approved