A128247 a(n) = A001783(n)/A038610(n).

1, 1, 1, 1, 2, 1, 12, 1, 8, 3, 1440, 1, 17280, 3, 112, 45, 29030400, 1, 522547200, 3, 12800, 945, 4828336128000, 1, 38626689024, 4725, 512512000, 2025, 3796230997278720000, 1, 113886929918361600000, 42525, 10436608000, 1403325, 551910745571328, 175

Offset

1,5

Links

T. D. Noe, Table of n, a(n) for n = 1..200

Example

The positive integers which are <= 10 and are coprime to 10 are 1,3,7,9. So a(10) = 1*3*7*9/lcm(1,3,7,9) = 189/63 = 3.

Mathematica

Table[s = Select[Range[1, n], GCD[#, n] == 1 &]; (Times @@ s)/(LCM @@ s), {n, 30}] (* T. D. Noe, Oct 04 2012 *)

Prog

(Sage)
def Gauss_factorial(N, n): return mul(j for j in (1..N) if gcd(j, n) == 1)
def L(N, n): return lcm([j for j in (1..N) if gcd(j, n) == 1])
def A128247(n): return Gauss_factorial(n, n)/L(n, n)
[A128247(n) for n in (1..34)] # Peter Luschny, Oct 02 2012

Crossrefs

Cf. A038610, A001783.

Sequence in context: A112284 A167401 A069249 * A161150 A163088 A105608

Adjacent sequences: A128244 A128245 A128246 * A128248 A128249 A128250

Keyword

nonn

Author

Leroy Quet, May 03 2007

Extensions

More terms from Sean A. Irvine, Jun 21 2011

Status

approved