A211349 Primes p such that p-1 divides 2^p + 2.

2, 3, 11, 251, 5051, 16811, 2025251, 8751251, 16607051, 28257611, 69005051, 78906251, 176775251, 210381251, 372175451, 550427051, 707025251, 854704451, 1866788051, 2441406251, 2605806251, 4249701251, 5469531251, 9304386251, 10315761251, 10915095251

Offset: 1

Author

Philip A. Hoskins, Feb 06 2013

Keywords

• nonn

Comments

Prime p>2 is in this sequence iff (p-1)/2 is in A015950. - Max Alekseyev, Dec 26 2017

Links

• Max Alekseyev, Table of n, a(n) for n = 1..177

Crossrefs

Cf. A069051, A211203.

Programs

Mathematica

Select[Prime[Range[1000]], Mod[2^# + 2, # - 1] == 0 &]

PARI

N=10^9;
default(primelimit,N);
forprime(p=2,N, if (-2==Mod(2,p-1)^p, print1(p,", ")));
/* Joerg Arndt, Feb 06 2013 */

Python

from sympy import primerange
A211349_list = [p for p in primerange(1,10**6) if p == 2 or pow(2,p,p-1) == p-3] # Chai Wah Wu, Mar 25 2021

Extensions

a(19)-a(47) from Giovanni Resta, Feb 10 2013

a(48)-a(177) from Max Alekseyev, Jan 06 2018