

A237251


Primes p such that p*2^(p1)1 is prime.


0




OFFSET

1,1


COMMENTS

The fifth Fermat prime, 65537, is not in the sequence: 65537*2^655361 is composite (per PFGW).  Michael B. Porter, Feb 11 2014
Also 65537*2^655361 is divisible by 16267 and 2058772459.  Jeppe Stig Nielsen, Jan 04 2020


LINKS

Table of n, a(n) for n=1..6.


PROG

(PARI) isok(p) = isprime(p) && isprime(p*2^(p1)  1); \\ Michel Marcus, Feb 06 2014


CROSSREFS

Cf. A019434, A092506, A230769, A236752.
Sequence in context: A087911 A265426 A099936 * A275584 A092506 A275159
Adjacent sequences: A237248 A237249 A237250 * A237252 A237253 A237254


KEYWORD

nonn,more,hard


AUTHOR

Gerasimov Sergey, Feb 05 2014


EXTENSIONS

a(5) from Ralf Stephan, Feb 03 2014
a(6) = A230769(26)+1 appended by Jeppe Stig Nielsen, Jan 04 2020


STATUS

approved



