This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A049544 #19 Jul 20 2025 10:11:27
%S A049544 2,23,31,47,71,89,113,127,167,191,223,233,239,257,263,281,311,353,359,
%T A049544 383,431,439,479,503,593,599,601,617,647,719,727,743,839,863,881,887,
%U A049544 911,919,983,1031,1049,1097,1103,1151,1193,1217,1223,1289,1319,1327
%N A049544 Primes p such that x^12 = 2 has a solution mod p.
%C A049544 Complement of A059264 relative to A000040. - _Vincenzo Librandi_, Sep 13 2012
%H A049544 R. J. Mathar, <a href="/A049544/b049544.txt">Table of n, a(n) for n = 1..1000</a>
%H A049544 <a href="/index/Pri#smp">Index entries for related sequences</a>
%e A049544 0^12 == 2 (mod 2). 2^12 == 2 (mod 23). 8^12 == 2 (mod 31). 4^12 == 2 (mod 47). 8^12 == 2 (mod 71). 2^12 == 2 (mod 89). 3^12 == 2 (mod 113). 8^12 == 2 (mod 127). - _R. J. Mathar_, Jul 20 2025
%t A049544 ok[p_]:= Reduce[Mod[x^12- 2, p] == 0, x, Integers]=!=False; Select[Prime[Range[200]], ok] (* _Vincenzo Librandi_, Sep 13 2012 *)
%o A049544 (Magma) [p: p in PrimesUpTo(1400) | exists(t){x : x in ResidueClassRing(p) | x^12 eq 2}]; // _Vincenzo Librandi_, Sep 13 2012
%Y A049544 Cf. A000040, A059264.
%K A049544 nonn,easy
%O A049544 1,1
%A A049544 _N. J. A. Sloane_