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A015922 Numbers n such that 2^n == 8 (mod n). 18
1, 2, 3, 4, 8, 9, 15, 21, 33, 39, 51, 57, 63, 69, 87, 93, 111, 123, 129, 141, 159, 177, 183, 195, 201, 213, 219, 237, 248, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Zak Seidov and Michael De Vlieger, Table of n, a(n) for n = 1..29055 (first 6822 terms from Zak Seidov)

OEIS Wiki, 2^n mod n

MATHEMATICA

a015922Q[n_Integer] := If[Mod[2^n, n] == Mod[8, n], True, False];

a015922[n_Integer] :=

Flatten[Position[Thread[a015922Q[Range[n]]], True]];

a015922[1000000] (* Michael De Vlieger, Jul 16 2014 *)

m = 8; Join[Select[Range[m], Divisible[2^# - m, #] &], Select[Range[m + 1, 10^3], PowerMod[2, #, #] == m &]] (* Robert Price, Oct 12 2018 *)

PROG

(PARI) isok(n) = Mod(2, n)^n == Mod(8, n); \\ Michel Marcus, Oct 13 2013, Jul 16 2014

CROSSREFS

Contains A033553 as a subsequence.

The odd terms form A276967.

Cf. A015921, A130133, A130134.

Sequence in context: A281089 A242333 A231811 * A212255 A078829 A045583

Adjacent sequences:  A015919 A015920 A015921 * A015923 A015924 A015925

KEYWORD

nonn

AUTHOR

Robert G. Wilson v

EXTENSIONS

First 5 terms added by David W. Wilson

STATUS

approved

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Last modified February 17 21:46 EST 2020. Contains 332006 sequences. (Running on oeis4.)