login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A188339 Primes p such that 2^p mod p^2 is prime. 1
5, 53, 61, 193, 227, 257, 307, 317, 383, 457, 577, 601, 607, 653, 727, 751, 947, 1019, 1031, 1039, 1049, 1093, 1123, 1193, 1259, 1283, 1409, 1471, 1483, 1607, 1613, 1667, 1987, 2011, 2029, 2203, 2357, 2371, 2377, 2909, 2939, 3011, 3049, 3089, 3163 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Felix Fröhlich, Table of n, a(n) for n = 1..3119 (All terms up to 10^6)

EXAMPLE

5 is a term because 5 is prime and (2^5 mod 5^2) = 32 mod 25 = 7 also prime.

MATHEMATICA

Select[Prime[Range[500]], PrimeQ[PowerMod[2, #, #^2]] &] (* Alonso del Arte, Mar 28 2011 *)

PROG

(PARI) forprime(p=2, 10^3, if(isprime(2^p%p^2), print1(p, ", "))) \\ Felix Fröhlich, Jun 28 2014

CROSSREFS

Cf. A066606.

Sequence in context: A257667 A045711 A090153 * A103654 A079385 A091272

Adjacent sequences:  A188336 A188337 A188338 * A188340 A188341 A188342

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Mar 28 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 8 14:52 EDT 2020. Contains 333314 sequences. (Running on oeis4.)