A007672 a(n) = A002034(n)!/n.

1, 1, 2, 6, 24, 1, 720, 3, 80, 12, 3628800, 2, 479001600, 360, 8, 45, 20922789888000, 40, 6402373705728000, 6, 240, 1814400, 1124000727777607680000, 1, 145152, 239500800, 13440, 180, 304888344611713860501504000000

Offset: 1

Author

N. J. A. Sloane, Robert G. Wilson v

Keywords

• nonn
• nice

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• A. J. Kempner, Miscellanea, Amer. Math. Monthly, 25 (1918), 201-210 [ See Section II, "Concerning the smallest integer m! divisible by a given integer n". ]

Programs

Mathematica

a[n_] := Module[{m = 1, x = n, as = 1, p}, While[x > 1, m++; p = GCD[x, m]; x = x/p; as *= m/p]; as]; Array[a, 30] (* Jean-François Alcover, May 09 2017, after Antonio Roldán *)

PARI

a(n)={local(m=1,x=n,as=1,p);while(x>1,m++;p=gcd(x,m);x=x/p;as*=m/p);as} \\ Antonio Roldán, Apr 04 2015