OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..300
Wikipedia, Counting lattice paths
EXAMPLE
: a(3) = 2:
:
: /\ /\
: /\/ \ / \/\ .
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 11 2017
STATUS
approved