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.
FORMULA
a(n) = Sum_{k=0..n} A274372(k,n).
EXAMPLE
/\ /\
a(5) = 3: /\/ \ / \/\ /\/\/\/\/\ .
.
/\
\ \ /\ /\ /\
a(6) = 5: / \ / \/\/\ /\/ \/\ /\/\/ \ /\/\/\/\/\/\ .
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 19 2016
STATUS
approved