A157359 Quatro-safe primes.

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

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Feb 27 2009

Keywords

• nonn

Comments

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

Crossrefs

Cf. A005385, A066179, A157357, A157358

Programs

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 *)