A064031 Product of non-unitary divisors of n!.

1, 1, 1, 576, 207360000, 26956124946896309452800000000000, 2841003716170671644367609186370356458508919205193278721884160000000000000000000000

Offset: 1

Author

Labos Elemer, Sep 13 2001

Keywords

• nonn

Examples

			n=6: 720 has 22 non-unitary divisors: a(6)=720^11=26956124946896309452800000000000
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10

Crossrefs

Cf. A048656, A048657, A061537, A061538, A000142, A048105, A000005, A034444.

Programs

Mathematica

a[n_] := (n!)^(DivisorSigma[0, n!]/2 - 2^(PrimePi[n]-1)); Array[a, 10] (* Amiram Eldar, Jul 16 2019 *)

Formula

a(n) = A061538(n!) = (n!)^(A048105(n!)/2) = (n!)^((A000005(n!)-A034444(n!))/2)