OFFSET
1,2
COMMENTS
It is conjectured that this is n iff n is 1 or a prime.
REFERENCES
R. K. Guy, Unsolved Problems Number Theory, A17.
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..1000
MATHEMATICA
Table[n/Denominator[(Sum[m^(n - 1), {m, n - 1}] + 1)/n], {n, 10}] (* Indranil Ghosh, May 17 2017 *)
PROG
(PARI) a(n) = n/denominator((sum(m=1, n - 1, m^(n - 1)) + 1)/n); \\ Indranil Ghosh, May 17 2017
(Python)
from sympy import Integer
def a(n): return Integer(n)/((sum(m**(n - 1) for m in range(1, n)) + 1)/Integer(n)).denominator() # Indranil Ghosh, May 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 11 2000
STATUS
approved