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A055032 Denominator of (Sum(m^(n-1),m=1..n-1)+1)/n. 8
1, 1, 1, 4, 1, 3, 1, 8, 9, 5, 1, 12, 1, 7, 15, 16, 1, 9, 1, 20, 7, 11, 1, 24, 25, 13, 27, 28, 1, 15, 1, 32, 33, 17, 35, 36, 1, 19, 13, 40, 1, 21, 1, 44, 45, 23, 1, 48, 49, 25, 51, 52, 1, 27, 55, 56, 19, 29, 1, 60, 1, 31, 63, 64, 65, 33, 1, 68, 69, 35, 1, 72, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

It is conjectured that this is 1 iff n is 1 or a prime.

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, A17.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

a:= proc(n) local S, m;

    S:= 1;

    for m from 1 to n-1 do

      S:= S + m &^(n-1) mod n;

    od:

    denom(S/n);

end proc;

seq(a(n), n=1..1000); # Robert Israel, May 30 2014

MATHEMATICA

Table[Denominator[(Sum[m^(n - 1), {m, 1, n - 1}] + 1)/n], {n, 1, 10}] (* G. C. Greubel, Jun 06 2016 *)

PROG

(PARI) a(n) = denominator((sum(m=1, n - 1, m^(n - 1)) + 1)/n); \\ Indranil Ghosh, May 17 2017

(Python)

from fractions import Fraction

def a(n): return Fraction(str(sum([m**(n - 1) for m in range(1, n)]) + 1) + "/" + str(n)).denominator # Indranil Ghosh, May 17 2017

CROSSREFS

Cf. A055031, A055030, A055023, A201560, A204187.

Sequence in context: A263022 A326690 A323072 * A039930 A123251 A327357

Adjacent sequences:  A055029 A055030 A055031 * A055033 A055034 A055035

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Jun 11 2000

STATUS

approved

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Last modified April 1 12:43 EDT 2020. Contains 333159 sequences. (Running on oeis4.)