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%I #10 Sep 08 2022 08:45:02
%S 1217,1249,1553,1777,2833,4049,4273,4481,4993,5297,6449,6481,6689,
%T 7121,8081,8609,9137,9281,9649,10337,10369,10433,11329,11617,11633,
%U 12241,12577,13121,13441,13633,14321,14753,15121,15569,16417,16433,16673
%N Primes p such that x^16 = 2 has no solution mod p, but x^8 = 2 has a solution mod p.
%H Vincenzo Librandi, <a href="/A059287/b059287.txt">Table of n, a(n) for n = 1..150</a>
%t Select[Prime[Range[PrimePi[20000]]], !MemberQ[PowerMod[Range[#], 16, #], Mod[2, #]] && MemberQ[PowerMod[Range[#], 8, #], Mod[2, #]]&] (* _Vincenzo Librandi_, Sep 21 2013 *)
%o (Magma) [p: p in PrimesUpTo(17000) | not exists{x: x in ResidueClassRing(p) | x^16 eq 2} and exists{x: x in ResidueClassRing(p) | x^8 eq 2}]; // _Vincenzo Librandi_, Sep 21 2012
%Y A000040, A045315, A045316.
%K nonn,easy
%O 1,1
%A _Klaus Brockhaus_, Jan 25 2001
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