A269453 The order of 2 mod m when m is the product of two distinct safe primes.

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

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: A289980 A109547 A334418 * A082800 A026041 A299028

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