A253901 a(n) = Product_{d divides n} ((d-1)!)^moebius(n/d).

1, 1, 2, 6, 24, 60, 720, 840, 20160, 15120, 3628800, 55440, 479001600, 8648640, 1816214400, 259459200, 20922789888000, 147026880, 6402373705728000, 55870214400, 1689515283456000, 14079294028800, 1124000727777607680000, 771008958720, 25852016738884976640000, 32382376266240000, 10002268381116211200000

Offset: 1

Author

Joerg Arndt, Jan 18 2015

Keywords

• nonn

Crossrefs

Cf. A250269: Product_{d divides n} (d!)^moebius(n/d).

Programs

PARI

a(n)={my(r=1);fordiv(n,d,r*=((d-1)!)^moebius(n/d));r}

Formula

(n-1)! = Product_{d divides n} a(d).