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A049550 Primes p such that x^18 = 2 has a solution mod p. 6
2, 17, 23, 31, 41, 47, 71, 89, 113, 127, 137, 167, 191, 223, 233, 239, 257, 263, 281, 311, 353, 359, 383, 401, 431, 439, 449, 457, 479, 503, 521, 569, 593, 599, 601, 617, 641, 647, 719, 727, 743, 761, 809, 839, 857, 863, 881, 887, 911, 929, 953, 977, 983 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Coincides with sequence of primes p such that x^54 = 2 has a solution mod p for the first 167 terms (and then diverges).

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..1000

Index entries for related sequences

MATHEMATICA

ok[p_]:= Reduce[Mod[x^18- 2, p] == 0, x, Integers]=!=False; Select[Prime[Range[200]], ok] (* Vincenzo Librandi, Sep 13 2012 *)

PROG

(PARI) forprime(p=2, 2000, if([]~!=polrootsmod(x^18-2, p), print1(p, ", "))); print();

/* Joerg Arndt, Jul 27 2011 */

(MAGMA) [p: p in PrimesUpTo(1000) | exists(t){x : x in ResidueClassRing(p) | x^18 eq 2}]; // Vincenzo Librandi, Sep 13 2012

CROSSREFS

Cf. A000040.

Sequence in context: A126961 A106622 A040992 * A049574 A018643 A094668

Adjacent sequences:  A049547 A049548 A049549 * A049551 A049552 A049553

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified October 1 15:55 EDT 2020. Contains 337443 sequences. (Running on oeis4.)