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A157359 Quatro-safe primes. 3
47, 1439, 2879, 858239, 861599, 982559, 1014719, 1067999, 2029439, 2034239, 2297759, 2683679, 2978399, 3301919, 4068479, 4288799, 4737599, 5454719, 6484319, 6753119, 7145759, 8624159, 9511199, 9717119, 10533599, 10739999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

(47-1)/2=23,(23-1)/2=11,(11-1)/2=5,(5-1)/2=2(prime),...

LINKS

Table of n, a(n) for n=1..26.

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[a=(p-1)/2]&&PrimeQ[b=(a-1)/2]&&PrimeQ[c=(b-1)/2]&&PrimeQ[(c-1)/2], AppendTo[lst, p]], {n, 10!}]; lst

Select[Prime[Range[711000]], AllTrue[Rest[NestList[(#-1)/2&, #, 4]], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 31 2018 *)

CROSSREFS

Cf. A005385, A066179, A157357, A157358

Sequence in context: A047911 A009069 A285237 * A153214 A142845 A202128

Adjacent sequences:  A157356 A157357 A157358 * A157360 A157361 A157362

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

STATUS

approved

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Last modified July 4 11:45 EDT 2020. Contains 335448 sequences. (Running on oeis4.)