A001916 Primes p such that the congruence 2^x = 5 (mod p) is solvable.

2, 3, 11, 13, 19, 29, 37, 41, 53, 59, 61, 67, 71, 79, 83, 101, 107, 131, 139, 149, 163, 173, 179, 181, 191, 197, 199, 211, 227, 239, 251, 269, 271, 293, 311, 317, 347, 349, 359, 373, 379, 389, 401, 409, 419, 421, 443, 449, 461, 467, 479, 491, 509, 521, 523, 541, 547, 557

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

References

• M. Kraitchik, Recherches sur la Théorie des Nombres. Gauthiers-Villars, Paris, Vol. 1, 1924, Vol. 2, 1929, see Vol. 1, p. 64.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001915.

Programs

Mathematica

Select[Prime[Range[120]], MemberQ[Table[Mod[2^x-5, #], {x, 0, #}], 0]&] (* Jean-François Alcover, Aug 29 2011 *)

Extensions

Better description and more terms from David W. Wilson, Dec 12 2000

Description corrected by Joe K. Crump (joecr(AT)carolina.rr.com), Jan 17 2001