A124493 Numbers k for which 2*k-1, 4*k-1 and 8*k-1 are primes.

3, 6, 21, 45, 90, 180, 255, 360, 510, 516, 615, 705, 726, 741, 756, 906, 945, 951, 966, 1230, 1350, 1410, 1725, 1746, 1770, 1911, 1956, 2541, 2700, 2721, 2925, 3051, 3066, 3225, 3540, 3576, 3675, 3951, 4485, 4611, 5295, 5346, 5355, 5586, 5736, 5775, 5901

Offset: 1

Author

Artur Jasinski, Nov 04 2006

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006254, A124485, A124494, A124017, A125113, A124514, A124515, A124516.

Programs

Mathematica

Select[3*Range[2000], And @@ PrimeQ /@ ({2, 4, 8}*# - 1) &] (* Ray Chandler, Nov 22 2006 *)