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A269453 The order of 2 mod m when m is the product of two distinct safe primes. 0
12, 20, 30, 44, 33, 92, 110, 116, 69, 174, 164, 230, 212, 246, 290, 318, 332, 356, 410, 253, 452, 249, 530, 534, 524, 638, 678, 692, 716, 830, 393, 902, 764, 890, 932, 956, 1038, 1166, 1130, 537, 1004, 573, 1334, 1124, 1310, 1172, 1398, 717, 753, 1436, 1730, 913, 1886, 1686, 1790 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The smallest positive integer k for which 2^k == 1 (mod m) where m = p*q with p, q distinct safe primes.

LINKS

Table of n, a(n) for n=1..55.

FORMULA

a(n) is the order of 2 modulo A157352(n). - Wolfdieter Lang, Mar 31 2016

MATHEMATICA

MultiplicativeOrder[2, #] & /@ Select[Select[Range@ 4200, PrimeNu@ # == 2 &], Times @@ Map[If[PrimeQ[(# - 1)/2], #, 0] &, Map[First, FactorInteger@ #]] == # &] (* Michael De Vlieger, Feb 28 2016 *)

CROSSREFS

Cf. A002326, A157352, A269452.

Sequence in context: A256883 A124672 A109547 * A082800 A026041 A082296

Adjacent sequences:  A269450 A269451 A269452 * A269454 A269455 A269456

KEYWORD

nonn

AUTHOR

Marina Ibrishimova, Feb 27 2016

EXTENSIONS

More terms from Michael De Vlieger, Feb 28 2016

STATUS

approved

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Last modified March 29 10:52 EDT 2017. Contains 284268 sequences.