OFFSET
1,2
COMMENTS
The PFGW program has been used to certify all the terms up to a(28), using a deterministic test which exploits the factorization of a(n)+1.
a(29) > 290000.
MATHEMATICA
Select[Range[1000], PrimeQ[Prime[#]*2^# - 1] &]
PROG
(Magma) [n: n in [0..1000] | IsPrime(NthPrime(n)*2^n-1)]; // Vincenzo Librandi, Dec 24 2015
(PARI) is(n, p=prime(n))=ispseudoprime(p<<n-1) \\ Charles R Greathouse IV, Jun 06 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Giovanni Resta, Mar 26 2014
STATUS
approved