OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..800
EXAMPLE
a(3) = 10: 3aab, 3abb, 2aa1b, 2ab1a, 2ab1b, 2bb1a, 1a2ab, 1a2bb, 1b2aa, 1b2ab.
MAPLE
b:= proc(n, i, k, p) option remember; `if`(n=0, p!,
`if`(i<1, 0, add(b(n-i*j, min(n-i*j, i-1), k, p+j)*
binomial(binomial(k+i-1, i), j), j=0..n/i)))
end:
a:= n-> (k-> add(b(n$2, i, 0)*(-1)^(k-i)*binomial(k, i), i=0..k))(2):
seq(a(n), n=0..37);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 27 2019
STATUS
approved