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A038922

Primes p such that 42 is not a square mod p.

5, 23, 31, 37, 43, 59, 67, 71, 73, 83, 97, 101, 103, 109, 113, 131, 137, 163, 173, 191, 199, 211, 223, 227, 233, 239, 241, 251, 263, 269, 271, 277, 281, 293, 313, 331, 359, 367, 373, 379, 401, 409, 419, 421, 431

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OFFSET

1,1

LINKS

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

MATHEMATICA

Select[Prime@Range[120], JacobiSymbol[42, #] == -1 &] (* Vincenzo Librandi, Sep 09 2012 *)

PROG

(PARI) select(n->!issquare(Mod(42, n)), primes(100)) \\ Charles R Greathouse IV, Sep 09 2012

(Magma) [p: p in PrimesUpTo(431) | not IsSquare(R! 42) where R:= ResidueClassRing(p)]; // Vincenzo Librandi, Sep 10 2012

(Magma) [p: p in PrimesInInterval(3, 431) | JacobiSymbol(42, p) eq -1]; // Bruno Berselli, Sep 10 2012

CROSSREFS

Sequence in context: A140386 A105880 A163587 * A019367 A065867 A082283

Adjacent sequences: A038919 A038920 A038921 * A038923 A038924 A038925

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

Offset changed from 0 to 1 by Vincenzo Librandi, Sep 09 2012

STATUS

approved

URL: https://oeis.org/A038922

⇱ A038922 - OEIS