

A175236


Primes p such that 2^p+23 is also prime.


1




OFFSET

1,1


COMMENTS

a(9) > 5*10^5.  Robert Price, Sep 18 2015


LINKS

Table of n, a(n) for n=1..8.


FORMULA

A057203 INTERSECT A000040. [R. J. Mathar, Jul 06 2010]


EXAMPLE

For p=3, 2^3+23=31; p=7, 2^7+23=131; p=79, 2^79+23=604462909807314587353111


MATHEMATICA

Select[Prime[Range[1000]], PrimeQ[2^#+23]&] (*Robert Price, Sep 18 2015 *)


PROG

(Magma) [p: p in PrimesUpTo(1000)  IsPrime(2^p+23) ]


CROSSREFS

Sequence in context: A181554 A116294 A077793 * A343763 A045974 A001531
Adjacent sequences: A175233 A175234 A175235 * A175237 A175238 A175239


KEYWORD

nonn


AUTHOR

Vincenzo Librandi, Mar 09 2010


EXTENSIONS

Two more terms from R. J. Mathar, Jul 06 2010
a(7)a(8) from Robert Price, Sep 18 2015


STATUS

approved



