A276400 Denominator of n!/(n^n-n).

1, 4, 21, 26, 1555, 817, 299593, 134521, 12345679, 43229041, 67546215517, 4622635937, 61054982558011, 18617937516193, 5118976599431, 4224061794762749, 128583032925805678351, 655879001624535409, 275941052631578947368421, 286115209221463953761, 2707038020425761202263187

Offset

2,2

Links

Chai Wah Wu, Table of n, a(n) for n = 2..389

Natasha Morrison and Alex Scott, Maximizing the number of induced cycles in a graph, Preprint, 2016. See Conj. 1.1.

Example

1, 1/4, 2/21, 1/26, 24/1555, 5/817, 720/299593, 126/134521, 4480/12345679, 6048/43229041, 3628800/67546215517, 95040/4622635937, 479001600/61054982558011, ...

Mathematica

Table[Denominator[n! / (n^n - n)], {n, 2, 30}] (* Vincenzo Librandi, Sep 12 2016 *)

Prog

(Python)
from __future__ import division
from math import factorial
from fractions import gcd
def A276400(n):
    a = n**(n-1) - 1
    return a//gcd(factorial(n-1), a) # Chai Wah Wu, Sep 11 2016
(Magma) [Denominator(Factorial(n)/(n^n-n)): n in [2..25]]; // Vincenzo Librandi, Sep 12 2016

Crossrefs

Cf. A276399.

Sequence in context: A041821 A042429 A356357 * A304770 A316513 A273208

Adjacent sequences: A276397 A276398 A276399 * A276401 A276402 A276403

Keyword

nonn,frac

Author

N. J. A. Sloane, Sep 11 2016

Status

approved