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A124416 Numbers n such that 2n+1, 4n+1, 8n+1, 16n+1, 32n+1, 64n+1, 128n+1 and 256n+1 are primes. 1
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

Table of n, a(n) for n=1..20.

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 A214194

Adjacent sequences:  A124413 A124414 A124415 * A124417 A124418 A124419

KEYWORD

nonn,changed

AUTHOR

Artur Jasinski, Nov 02 2006

EXTENSIONS

Extended by Ray Chandler, Nov 21 2006

STATUS

approved

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Last modified February 25 22:55 EST 2020. Contains 332270 sequences. (Running on oeis4.)