A124415 Numbers k such that 2*k+1, 4*k+1, 8*k+1, 16*k+1, 32*k+1, 64*k+1 and 128*k+1 are primes.

8325, 82950, 884220, 1120470, 3441690, 5627895, 5765505, 7664745, 7757430, 8555040, 10739505, 11891625, 15514860, 15623475, 18268455, 22631970, 24833775, 27373410, 29342895, 31286970, 31577205, 50077455, 51541035, 58646520

Offset: 1

Author

Artur Jasinski, Nov 02 2006

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005097, A123998, A124041, A124412-A124417.

Programs

Mathematica

Select[15*Range[4000000], And @@ PrimeQ /@ ({2, 4, 8, 16, 32, 64, 128}*# + 1) &] (* Ray Chandler, Nov 21 2006 *)
Select[Range[15,59*10^6,15],AllTrue[2^Range[7] #+1,PrimeQ]&]  (* Harvey P. Dale, Jan 19 2025 *)

Extensions

Corrected and extended by Ray Chandler, Nov 21 2006