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A213049 Primes p such that the order of 2 mod p is a square. 1
5, 37, 73, 101, 109, 197, 257, 577, 601, 641, 677, 727, 1601, 1801, 2593, 3137, 3389, 3457, 4057, 4357, 5477, 8101, 8837, 10369, 14401, 14407, 16901, 17957, 18253, 18433, 20809, 21317, 22501, 25601, 30977, 33857, 37447, 42437, 44101, 47629, 47653, 50177 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..178

EXAMPLE

The order of 2 mod 601 is 25, which is a square, so 601 is a term.

PROG

(PARI)

{ forprime (p=3, 10^6,

    r = znorder(Mod(2, p));

    if ( issquare(r), print1(p, ", ") );

); }

(MAGMA) [NthPrime(n): n in [2..6275] | IsSquare(Modorder(2, NthPrime(n)))]; // Bruno Berselli, Jun 08 2012

CROSSREFS

Cf. A014662, A014663, A122094.

Sequence in context: A127589 A244374 A238477 * A031913 A188130 A054587

Adjacent sequences:  A213046 A213047 A213048 * A213050 A213051 A213052

KEYWORD

nonn

AUTHOR

Joerg Arndt, Jun 03 2012

STATUS

approved

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Last modified August 9 01:17 EDT 2020. Contains 336310 sequences. (Running on oeis4.)