OFFSET
0,5
LINKS
Czabarka, É., Flórez, R., Junes, L., & Ramírez, J. L., Enumerations of peaks and valleys on non-decreasing Dyck paths, Discrete Mathematics (2018), 341(10), 2789-2807.
FORMULA
Conjectures from Colin Barker, Oct 28 2018: (Start)
G.f.: x^3*(1 - x)^2 / ((1 - 2*x)^2*(1 - 3*x + x^2)).
a(n) = 7*a(n-1) - 17*a(n-2) + 16*a(n-3) - 4*a(n-4) for n>5.
(End)
MAPLE
a := n -> `if`(n < 2, 0, combinat:-fibonacci(2*n) - (n + 4)*2^(n - 3)):
seq(a(n), n=0..30); # Peter Luschny, Oct 28 2018
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 18 2018
EXTENSIONS
More terms from Peter Luschny, Oct 28 2018
STATUS
approved