OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..70
Beata Benyi, Anders Claesson, and Mark Dukes, Weak ascent sequences and related combinatorial structures, arXiv:2111.03159 [math.CO], 2021-2022.
FORMULA
a(n) = A369321(2n,n).
MAPLE
b:= proc(n, i, t) option remember; expand(`if`(n=0, 1, add(
b(n-1, j, t+`if`(j>=i, 1, 0))*`if`(j>=i, x, 1), j=0..t+1)))
end:
a:= n-> coeff(b(2*n, -1$2), x, n):
seq(a(n), n=0..17);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, May 25 2024
STATUS
approved