A276969 Odd integers n such that 2^n == 2^7 (mod n).

1, 3, 7, 15, 49, 91, 133, 217, 255, 259, 301, 427, 469, 511, 527, 553, 679, 721, 763, 889, 973, 1015, 1057, 1099, 1141, 1267, 1351, 1393, 1477, 1561, 1603, 1687, 1897, 1939, 1981, 2107, 2149, 2191, 2317, 2359, 2443, 2569, 2611, 2653, 2779, 2863, 2947, 3031, 3073, 3199, 3241, 3409, 3493, 3661, 3787

Offset: 1

Author

Max Alekseyev, Sep 22 2016

Keywords

• nonn
• easy

Comments

Also, integers n such that 2^(n-7) == 1 (mod n).

Contains A208155 as a subsequence.

For all m, 2^A015922(m)-1 belongs to this sequence.

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..10000

Crossrefs

The odd terms of A015927.

Odd integers n such that 2^n == 2^k (mod n): A176997 (k=1), A173572 (k=2), A276967 (k=3), A033984 (k=4), A276968 (k=5), A215610 (k=6), this sequence (k=7), A215611 (k=8), A276970 (k=9), A215612 (k=10), A276971 (k=11), A215613 (k=12).

Cf. A015922, A208155.

Programs

Mathematica

m = 2^7; Join[Select[Range[1, m, 2], Divisible[2^# - m, #] &],
Select[Range[m + 1, 10^3, 2], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 12 2018 *)

PARI

is(n)=n%2 && Mod(2,n)^n==128 \\ Charles R Greathouse IV, Sep 22 2016