OFFSET
1,1
COMMENTS
Primes p such that 2*p+1, 4*p+3, 8*p+7, 16*p+15 and 32*p+31 are also primes. - Vincenzo Librandi, Aug 04 2010
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
FORMULA
a(n) == 29 (mod 30). - Zak Seidov, Jan 31 2013
MATHEMATICA
Select[Prime[Range[10^5]], PrimeQ[a1=2*#+1] && PrimeQ[a2=2*a1+1] && PrimeQ[a3=2*a2+1] && PrimeQ[a4=2*a3+1] && PrimeQ[a5=2*a4+1] &] (* Vladimir Joseph Stephan Orlovsky, May 01 2008 *)
PROG
(Magma) [n: n in [1..5000000] | forall{2^i*n+2^i-1: i in [0..5] | IsPrime(2^i*n+2^i-1)}]; // Vincenzo Librandi, Aug 04 2010
(PARI) is(n)=isprime(n) && isprime(2*n+1) && isprime(4*n+3) && isprime(8*n+7) && isprime(16*n+15) && isprime(32*n+31) \\ Charles R Greathouse IV, Jul 01 2013
(Python)
from sympy import prime, isprime
A023330_list = [p for p in (prime(n) for n in range(1, 10**5)) if all([isprime(2**m*(p+1)-1) for m in range(1, 6)])] # Chai Wah Wu, Sep 09 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved