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A124416 Numbers k such that 2*k+1, 4*k+1, 8*k+1, 16*k+1, 32*k+1, 64*k+1, 128*k+1 and 256*k+1 are primes. 2
7757430, 31286970, 360821505, 365536215, 414779430, 418803000, 428547690, 428823900, 434768475, 508654155, 584808795, 732681630, 809814510, 846079035, 857095380, 968314215, 1115279880, 1187901285, 1193371860, 1244805450 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..100

MATHEMATICA

Select[15*Range[10^8], And @@ PrimeQ /@ ({2, 4, 8, 16, 32, 64, 128, 256}*# + 1) &] (* Ray Chandler, Nov 21 2006 *)

Select[15*Range[83*10^6], AllTrue[#*2^Range[8]+1, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 23 2020 *)

CROSSREFS

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

Sequence in context: A233597 A258954 A273101 * A320516 A319809 A347424

Adjacent sequences:  A124413 A124414 A124415 * A124417 A124418 A124419

KEYWORD

nonn

AUTHOR

Artur Jasinski, Nov 02 2006

EXTENSIONS

Extended by Ray Chandler, Nov 21 2006

STATUS

approved

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Last modified May 28 18:24 EDT 2022. Contains 354122 sequences. (Running on oeis4.)