A055031 Numerator of (Sum(m^(n-1),m=1..n-1)+1)/n.

1, 1, 2, 37, 71, 2213, 9596, 1200305, 24684613, 287152493, 1355849266, 427675990237, 1032458258547, 228796942438201, 16841089312342856, 665478473553144001, 1653031004194447737, 631449646252135295657, 3167496749732497119310

Offset: 1

Author

N. J. A. Sloane, Jun 11 2000

Keywords

• nonn
• frac

References

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

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A055032, A055030, A055023, A201560, A204187.

Programs

Mathematica

Table[Numerator[(Sum[m^(n - 1), {m, n - 1}] + 1)/n], {n, 50}] (* Indranil Ghosh, May 17 2017 *)

PARI

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

Python

from sympy import Integer
def a(n): return ((sum(m**(n - 1) for m in range(1, n)) + 1)/Integer(n)).numerator # Indranil Ghosh, May 17 2017