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

1,1

Comments

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

Links

Table of n, a(n) for n=1..67.

Mathematica

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

Prog

(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 */

Crossrefs

Cf. A002326, A001122, A216838.

Sequence in context: A197354 A089399 A003619 * A288674 A183294 A039234

Adjacent sequences: A216843 A216844 A216845 * A216847 A216848 A216849

Keyword

nonn

Author

V. Raman, Sep 17 2012

Status

approved