A282989 Primes p such that q = 2*p^3-1, r = 2*q^3-1 and s = 2*r^3-1 are also prime.

208291, 958333, 2239723, 5203453, 5437951, 6677623, 6954421, 9232843, 13078531, 13142011, 15345763, 17670481, 20282551, 21415321, 23547283, 23694883, 25262623, 25550113, 26642491, 27425521, 29851993, 30327421

Offset

1,1

Comments

Primes p such that A283020(i) > 2, where i is the index of p in A000040. - Felix Fröhlich, Feb 26 2017

Links

Table of n, a(n) for n=1..22.

Pierre CAMI, PFGW Script

Mathematica

Select[Prime@ Range[10^6], Times @@ Boole@ PrimeQ@ NestList[2 #^3 - 1 &, #, 3] > 0 &] (* Michael De Vlieger, Feb 26 2017 *)

Prog

(PARI) is(n) = my(q=2*n^3-1, r=2*q^3-1, s=2*r^3-1); ispseudoprime(n) && ispseudoprime(q) && ispseudoprime(r) && ispseudoprime(s) \\ Felix Fröhlich, Feb 26 2017

Crossrefs

Cf. A177104, A283020.

Sequence in context: A072679 A147705 A237971 * A233663 A232136 A183602

Adjacent sequences: A282986 A282987 A282988 * A282990 A282991 A282992

Keyword

nonn

Author

Pierre CAMI, Feb 26 2017

Status

approved