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A015921
Positive integers n such that 2^n == 4 (mod n).
18
1, 2, 4, 6, 10, 12, 14, 22, 26, 30, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 132, 134, 142, 146, 158, 166, 170, 178, 182, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 372, 382, 386, 394, 398, 422, 446
OFFSET
1,2
COMMENTS
Odd terms are given by A173572.
For all m, 2^A050259(m)-1 belongs to this sequence.
LINKS
MATHEMATICA
Select[Range[500], PowerMod[2, #, #] == 4 &] (* Alonso del Arte, Jul 07 2011 *)
CROSSREFS
Contains A050990 as a subsequence.
Sequence in context: A301646 A024892 A087136 * A232964 A348442 A132631
KEYWORD
nonn
EXTENSIONS
Edited and terms 1,2,4 prepended by Max Alekseyev, Jul 29 2011
STATUS
approved