OFFSET
6,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 6..452
MAPLE
b:= proc(u, o, c, k) option remember;
`if`(c<0 or c>k, 0, `if`(u+o=0, 1,
add(b(u-j, o-1+j, c+1, k), j=1..u)+
add(b(u+j-1, o-j, c-1, k), j=1..o)))
end:
a:= n-> b(n, 0$2, 6)-b(n, 0$2, 5):
seq(a(n), n=6..24);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 01 2018
STATUS
approved