A014949 Numbers k that divide 8^k - 1.

1, 7, 49, 343, 889, 2359, 2401, 6223, 16513, 16807, 43561, 112903, 115591, 117649, 299593, 304927, 790321, 794983, 809137, 823543, 2033143, 2097151, 2134489, 5532247, 5564881, 5663959, 5764801, 13549249, 14232001, 14338681, 14680057, 14941423, 34591207, 38048311, 38725729

Offset: 1

Author

Olivier Gérard

Keywords

• nonn

Comments

For all m, 7^m is in the sequence. - Benoit Cloitre, Mar 05 2002

From Alexander Adamchuk, May 16 2010: (Start)

7 divides a(n) for n>1.

Prime divisors of a(n) in the order of their first appearance are {7, 127, 337, 2287, 15241, 14407, 18199, 42463, ...}. (End)

Links

• M. F. Hasler, Table of n, a(n) for n = 1..64

Crossrefs

Cf. A024088 (8^n-1).

Programs

PARI

is(n)=Mod(8,n)^n==1 \\ Charles R Greathouse IV, Nov 04 2016

Extensions

More terms from Benoit Cloitre, Mar 05 2002

a(15)-a(31) from Alexander Adamchuk, May 16 2010

More terms from M. F. Hasler, Nov 21 2018