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 A040147 #11 Jul 08 2025 22:52:07
%S A040147 2,5,11,19,29,31,59,61,71,79,131,139,151,179,191,199,211,229,239,251,
%T A040147 271,311,331,349,359,379,401,409,419,421,431,439,449,479,491,499,509,
%U A040147 521,569,571,599,619,631,659,661
%N A040147 Primes p such that x^4 = 20 has a solution mod p.
%H A040147 Vincenzo Librandi, <a href="/A040147/b040147.txt">Table of n, a(n) for n = 1..1000</a>
%t A040147 ok [p_]:=Reduce[Mod[x^4 - 20, p]== 0, x, Integers]=!= False; Select[Prime[Range[180]], ok] (* _Vincenzo Librandi_, Sep 12 2012 *)
%o A040147 (Magma) [p: p in PrimesUpTo(800) | exists(t){x : x in ResidueClassRing(p) | x^4 eq 20}]; // _Vincenzo Librandi_, Sep 12 2012
%Y A040147 Cf. A040148.
%K A040147 nonn,easy
%O A040147 1,1
%A A040147 _N. J. A. Sloane_