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A276967 Odd integers n such that 2^n == 2^3 (mod n). 7
1, 3, 9, 15, 21, 33, 39, 51, 57, 63, 69, 87, 93, 111, 123, 129, 141, 159, 177, 183, 195, 201, 213, 219, 237, 249, 267, 291, 303, 309, 315, 321, 327, 339, 381, 393, 399, 411, 417, 447, 453, 471, 489, 501, 519, 537, 543, 573, 579, 591, 597, 633, 669, 681, 687, 693, 699, 717, 723, 731, 753, 771, 789, 807 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also, integers n such that 2^(n - 3) == 1 (mod n).

Contains A033553 as a subsequence. Smallest term greater than 3 missing in A033553 is 731.

For all m, 2^A015921(m) - 1 belongs to this sequence.

LINKS

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

MATHEMATICA

Join[{1}, Select[Range[1, 1023, 2], PowerMod[2, # - 3, #] == 1 &]] (* Alonso del Arte, Sep 22 2016 *)

PROG

(PARI) isok(n) = (n % 2) && (Mod(2, n)^n==8); \\ Michel Marcus, Sep 23 2016

CROSSREFS

The odd terms of A015922.

Odd integers n such that 2^n == 2^k (mod n): A176997 (k = 1), A173572 (k = 2), this sequence (k = 3), A033984 (k = 4), A276968 (k = 5), A215610 (k = 6), A276969 (k = 7), A215611 (k = 8), A276970 (k = 9), A215612 (k = 10), A276971 (k = 11), A215613 (k = 12).

Sequence in context: A162486 A067201 A071526 * A114271 A137164 A108701

Adjacent sequences:  A276964 A276965 A276966 * A276968 A276969 A276970

KEYWORD

nonn,easy

AUTHOR

Max Alekseyev, Sep 22 2016

STATUS

approved

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Last modified May 19 10:36 EDT 2019. Contains 323390 sequences. (Running on oeis4.)