OFFSET
3,6
LINKS
Wikipedia, Caterpillar tree
FORMULA
a(n) = A130131(n) - (2^(n-4) + 2^[(n-4)/2]).
EXAMPLE
All the trees of order less than 7 are caterpillars. Only one tree with 7 nodes is a lobster and is not a caterpillar, so a(3)=a(4)=a(5)=a(6)=0, and a(7)=1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Washington Bomfim, Feb 23 2011
STATUS
approved