OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..450
FORMULA
a(n) = A364310(2n,n).
EXAMPLE
a(2) = 5: 3abc1d, 3abd1c, 3acd1b, 3bcd1a, 22abcd.
MAPLE
b:= proc(n, i) option remember; expand(`if`(n=0, 1, `if`(i<1, 0,
add(b(n-i*j, i-1)*x^j*binomial(n, i*j), j=0..n/i))))
end:
a:= n-> coeff(b(2*n$2), x, n):
seq(a(n), n=0..23);
MATHEMATICA
b[n_, i_] := b[n, i] = Expand[If[n == 0, 1, If[i < 1, 0,
Sum[b[n - i*j, i - 1]*x^j*Binomial[n, i*j], {j, 0, n/i}]]]];
a[n_] := Coefficient[b[2n, 2n], x, n];
Table[a[n], {n, 0, 23}] (* Jean-François Alcover, Nov 29 2023, from Maple code *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 18 2023
STATUS
approved