A060084 a(n) is the least prime not a primitive root of n-th prime.

2, 3, 5, 2, 3, 3, 2, 5, 2, 5, 2, 3, 2, 2, 2, 7, 3, 3, 3, 2, 2, 2, 3, 2, 2, 5, 2, 3, 2, 2, 2, 3, 2, 5, 5, 2, 2, 5, 2, 13, 3, 3, 2, 2, 7, 2, 5, 2, 3, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 17, 2, 2, 2, 7, 2, 2, 3, 3, 2, 2, 2, 3, 5, 2, 5, 2, 2, 2, 3, 3, 2, 2, 2, 3, 2, 2, 5, 2, 3, 2, 2, 3, 2, 2, 5, 2, 3, 3, 3, 7, 3, 2, 2, 2

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

a(8) = 5 because 19 is the 8th prime, primes 2 and 3 are primitive roots of 19, but 5 is not.

Maple

with(numtheory); for n from 1 to 100 do i := 1; while (i < n) and (primroot(ithprime(i) - 1, ithprime(n)) = ithprime(i)) do i := i+1; od; print( ithprime(i)); od:

Mathematica

Flatten[Table[Take[Complement[Prime[Range[25]], PrimitiveRoot[Prime[n]]], 1], {n, 100}]] (* Alonso del Arte, Oct 23 2012 *)

Prog

(PARI) a(n)=my(q=prime(n)); forprime(p=2, q-1, if(znorder(Mod(p, q))<q-1, return(p))); q \\ Charles R Greathouse IV, Oct 26 2012

Crossrefs

Cf. A000040, A060085.

Sequence in context: A317358 A133907 A232931 * A374155 A361503 A265668

Adjacent sequences: A060081 A060082 A060083 * A060085 A060086 A060087

Keyword

easy,nonn

Author

Marc LeBrun, Feb 23 2001

Extensions

Corrected by Jud McCranie, Mar 14 2001. Checked by N. J. A. Sloane Sep 03 2002.

Status

approved