OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..26
FORMULA
a(n) = Sum_{j=0..n} (-1)^(n-j)*binomial(n,j)*(n*j)!/n!^j.
a(n) mod 2 = 1 - (n mod 2) = A059841(n).
EXAMPLE
a(2) = 5: 1212, 1221, 2112, 2121, 2211.
MAPLE
a:= n-> add((-1)^(n-j)*binomial(n, j)*(n*j)!/n!^j, j=0..n):
seq(a(n), n=0..10);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 24 2024
STATUS
approved