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A124485 Numbers n such that 2n-1 and 4n-1 are primes. 15
2, 3, 6, 12, 15, 21, 27, 42, 45, 57, 66, 87, 90, 96, 117, 120, 126, 141, 147, 180, 210, 216, 222, 246, 255, 297, 321, 327, 330, 342, 360, 372, 381, 405, 456, 477, 507, 510, 516, 525, 552, 612, 615, 645, 705, 720, 726, 741, 750, 756, 780, 792, 801, 867, 906, 945 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

MATHEMATICA

Select[Range[1000], And @@ PrimeQ /@ ({2, 4}*# - 1) &] (*Chandler*)

CROSSREFS

Cf. A124486-A124492.

Sequence in context: A110590 A111271 A070926 * A200175 A125867 A032727

Adjacent sequences:  A124482 A124483 A124484 * A124486 A124487 A124488

KEYWORD

nonn

AUTHOR

Artur Jasinski (grafix(AT)csl.pl), Nov 04 2006

EXTENSIONS

Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 21 2006

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Last modified February 16 16:00 EST 2012. Contains 205938 sequences.