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A216846 Union of the composite numbers and the primes for which 2 is a primitive root. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 21 13:55 EST 2020. Contains 331113 sequences. (Running on oeis4.)