OFFSET
1,2
LINKS
Mathilde Bouvel, Philippe Gambette and Marefatollah Mansouri, Maple worksheet
Mathilde Bouvel, Philippe Gambette and Marefatollah Mansouri, Counting Phylogenetic Networks of level 1 and 2, Version 2, arXiv:1909.10460 [math.CO], 2019.
FORMULA
Bouvel, Gambette and Mansouri provide (among other results) a closed formula for a(n), an equation for the associated exponential generating function, and an asymptotic estimate of a(n). See their Section 6.
EXAMPLE
a(3) = 282 is the number of unrooted level-2 phylogenetic networks with 4 labeled leaves.
MAPLE
# see links section
CROSSREFS
KEYWORD
nonn
AUTHOR
Mathilde Bouvel, Oct 04 2019
EXTENSIONS
Name clarified by Mathilde Bouvel, Feb 03 2020
STATUS
approved