A213049 Primes p such that the order of 2 mod p is a square.

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

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