OFFSET
0,5
COMMENTS
A modified skew Dyck path is a path in the first quadrant which begins at the origin, ends on the x-axis, consists of steps U=(1,1) (up), D=(1,-1) (down) and A=(-1,1) (anti-down) so that A and D steps do not overlap.
EXAMPLE
a(1) = 1: /\
.
/\
\ \
a(3) = 1: / \
.
/\ /\
/ \ /\/\/\ / \
a(4) = 3: /\/ \ , / \ , / \/\ .
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 19 2016
STATUS
approved