

A196303


Numbers n such that both n and (n1)*2^n+1 are primes.


0




OFFSET

1,1


COMMENTS

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


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

a(1)=2 because 2 and (21)*2^2+1=5 are both prime.
a(2)=3 because 3 and (31)*2^3+1=17 are both prime.
a(3)=7 because 7 and (71)*2^7+1=769 are both prime.


MATHEMATICA

Select[Prime[Range[9000]], PrimeQ[(#1)2^#+1]&] (* Harvey P. Dale, Jan 19 2012 *)


PROG

(PARI) forprime(n=1, 1e4, if(ispseudoprime((n1)<<n+1), print1(n", "))) \\ Charles R Greathouse IV, Oct 09 2011


CROSSREFS

Subsequence of A128001.
Cf. A029544, A196421, A196446.
Sequence in context: A238400 A266276 A088252 * A048979 A088332 A131959
Adjacent sequences: A196300 A196301 A196302 * A196304 A196305 A196306


KEYWORD

nonn


AUTHOR

JuriStepan Gerasimov, Oct 02 2011


STATUS

approved



