A015922 Numbers k such that 2^k == 8 (mod k).
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
Offset: 1
Keywords
Links
- Michael De Vlieger, Table of n, a(n) for n = 1..29055 (first 6822 terms from Zak Seidov)
- OEIS Wiki, 2^n mod n.
Crossrefs
Programs
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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 *) Join[{1,2,3,4,8},Select[Range[650],PowerMod[2,#,#]==8&]] (* Harvey P. Dale, Aug 22 2020 *)
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PARI
isok(n) = Mod(2, n)^n == Mod(8, n); \\ Michel Marcus, Oct 13 2013, Jul 16 2014
Extensions
First 5 terms inserted by David W. Wilson
Comments