login
Primes p such that 30 is not a square mod p.
4

%I #10 Oct 01 2013 17:57:28

%S 11,23,31,41,43,47,53,59,61,67,73,79,89,97,109,131,151,163,167,173,

%T 179,181,193,197,199,229,251,263,271,281,283,293,307,313,317,337,349,

%U 383,401,419,421,433,439,449,457

%N Primes p such that 30 is not a square mod p.

%C Also primes p such that p divides 6^(p-1)/2 + 5^(p-1)/2 - _Cino Hilliard_, Sep 06 2004

%C Primes p such that p divides 7^(p-1)/2 - 1. - _Cino Hilliard_, Sep 06 2004

%H Vincenzo Librandi, <a href="/A038904/b038904.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime@Range[120], JacobiSymbol[30, #] == -1 &] (* _Vincenzo Librandi_, Sep 09 2012 *)

%K nonn

%O 1,1

%A _N. J. A. Sloane_.