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A040150 Primes p such that x^4 = 21 has no solution mod p. 2
11, 13, 19, 23, 29, 31, 37, 41, 53, 61, 71, 73, 89, 97, 101, 103, 107, 113, 137, 139, 149, 157, 173, 179, 181, 191, 197, 199, 223, 229, 233, 239, 241, 257, 263, 271, 277, 281, 283, 293, 307, 313, 317, 347, 349 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Complement of A040149 relative to A000040. - Vincenzo Librandi, Sep 18 2012

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

ok[p_]:= Reduce[Mod[x^4 - 21, p] == 0, x, Integers] == False; Select[Prime[Range[100]], ok] (* Vincenzo Librandi, Sep 18 2012  *)

PROG

(MAGMA) [p: p in PrimesUpTo(500) | not exists{x : x in ResidueClassRing(p) | x^4 eq 21} ]; // Vincenzo Librandi, Sep 18 2012

CROSSREFS

Sequence in context: A030792 A101934 A164861 * A214629 A330696 A103803

Adjacent sequences:  A040147 A040148 A040149 * A040151 A040152 A040153

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified August 4 12:23 EDT 2020. Contains 336201 sequences. (Running on oeis4.)