A216846 Union of the composite numbers and the primes for which 2 is a primitive root.

3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 74, 75, 76, 77, 78

Offset: 1

Author

V. Raman, Sep 17 2012

Keywords

• nonn

Comments

This is the complement of A216838 (primes for which 2 is not a primitive root). [V. Raman, Dec 01 2012]

Crossrefs

Cf. A002326, A001122, A216838.

Programs

Mathematica

nn = 100; Union[Select[Range[2, nn], ! PrimeQ[#] &], Select[Prime[Range[2, PrimePi[nn]]], PrimitiveRoot[#] == 2 &]] (* T. D. Noe, Sep 19 2012 *)

PARI

for(i=1, 100, if(isprime(i), if(znorder(Mod(2, i))!=(i-1), print1(i, ", ")), print1(i, ", "))); /* V. Raman, Sep 17 2012 */

PARI

is_A216846(n) = if( !isprime(n), 1, if(znorder(Mod(2,n))==n-1, 1, 0) );
for(n=3,100,if(is_A216846(n),print1(n,", ")));
/* Joerg Arndt, Oct 15 2012 */