A007672 a(n) = A002034(n)!/n. (Formerly M1669)

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

1,3

References

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

Links

Table of n, a(n) for n=1..29.

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". ]

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 *)

Prog

(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

Crossrefs

Sequence in context: A327426 A086554 A213324 * A322255 A084337 A371359

Adjacent sequences: A007669 A007670 A007671 * A007673 A007674 A007675

Keyword

nonn,nice

Author

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

Status

approved