OFFSET
1,1
COMMENTS
This sequence is the union of the odd composite numbers and the primes for which 2 is not a primitive root.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
nn = 200; Union[Select[Range[3, nn, 2], ! PrimeQ[#] &], Select[Prime[Range[2, PrimePi[nn]]], PrimitiveRoot[#] =!= 2 &]] (* T. D. Noe, Sep 19 2012 *)
PROG
(PARI) for(i=4, 200, if(isprime(i), if(znorder(Mod(2, i))!=(i-1), print(i)), if(i%2==1, print(i))))
(PARI) for(i=0, 200, i++; if(matsize(factormod((x^i+1)/(x+1), 2, 1))[1]>1, print(i)))
CROSSREFS
KEYWORD
nonn
AUTHOR
V. Raman, Oct 04 2012
STATUS
approved