A051447 Integers n such that 2^n == 9 (mod n).

1, 7, 2228071, 16888457, 352978207, 1737848873, 77362855777, 567442642711

Offset: 1

Author

Joe K. Crump (joecr(AT)carolina.rr.com)

Keywords

• hard
• nonn
• more

Comments

No other terms below 10^15. [Max Alekseyev, May 20 2012]

Links

• Joe K. Crump, 2^n mod n

Crossrefs

Cf. A125000, A124974, A033983, A033982, A033981, A050259, A124977, A124965, A015911, A015910.

Cf. A033981, A033982, A033983.

Programs

Mathematica

m = 9; Join[Select[Range[m], Divisible[2^# - m, #] &],
Select[Range[m + 1, 10^3], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 08 2018 *)

Extensions

Edited by N. J. A. Sloane, Jun 22 2008, at the suggestion of Don Reble

Terms 1, 7 prepended by Max Alekseyev, May 18 2011