A276967 - OEIS

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A276967

Odd integers n such that 2^n == 2^3 (mod n).

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