A294134 Sorted list of prime factors of numbers of the form 7^(2^m) + 2^(2^m) with m >= 0.

3, 17, 53, 97, 257, 449, 2417, 7681, 8513, 65537, 89633, 114689, 339121, 876097, 1321729, 1454081, 2572289, 4638721, 5463041, 7340033, 27688961, 47047681, 62177153, 93847553, 113418241, 374734849, 3731619841, 13037142017, 13555990529, 13951408129, 142807662593

Offset

1,1

Comments

Primes p other than 5 such that the multiplicative order of 7/2 (mod p) is a power of 2.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..43

Anders Björn and Hans Riesel, Factors of generalized Fermat numbers, Math. Comp. 67 (1998), no. 221, pp. 441-446.

Anders Björn and Hans Riesel, Table errata to “Factors of generalized Fermat numbers”, Math. Comp. 74 (2005), no. 252, p. 2099.

Anders Björn and Hans Riesel, Table errata 2 to "Factors of generalized Fermat numbers", Math. Comp. 80 (2011), pp. 1865-1866.

Prog

(PARI) print1(3, ", "); forprime(p=17, 142807662593, z=znorder(Mod(7/2, p)); if(2^ispower(z)==z, print1(p, ", ")));

Crossrefs

Cf. A176946, A294132, A294133, A294135, A294136.

Sequence in context: A163943 A093418 A173733 * A258032 A361525 A033562

Adjacent sequences: A294131 A294132 A294133 * A294135 A294136 A294137

Keyword

nonn

Author

Arkadiusz Wesolowski, Oct 23 2017

Status

approved