OFFSET
1,3
FORMULA
(n-1)! = Product_{d divides n} a(d).
PROG
(PARI) a(n)={my(r=1); fordiv(n, d, r*=((d-1)!)^moebius(n/d)); r}
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Jan 18 2015
STATUS
approved