A294133 - OEIS

%I #12 Nov 02 2017 15:39:09

%S 7,17,29,97,193,257,641,12289,22993,65537,102593,115201,152833,211457,

%T 993793,5189633,26411009,79280897,93847553,167772161,230686721,

%U 1364951041,1573071713,3221225473,5488091137,186678460417,206158430209,274568286337

%N Sorted list of prime factors of numbers of the form 5^(2^m) + 2^(2^m) with m >= 0.

%C Primes p other than 3 such that the multiplicative order of 5/2 (mod p) is a power of 2.

%H Arkadiusz Wesolowski, <a href="/A294133/b294133.txt">Table of n, a(n) for n = 1..34</a>

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-98-00891-6">Factors of generalized Fermat numbers</a>, Math. Comp. 67 (1998), no. 221, pp. 441-446.

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-05-01816-8">Table errata to “Factors of generalized Fermat numbers”</a>, Math. Comp. 74 (2005), no. 252, p. 2099.

%H Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-10-02371-9">Table errata 2 to "Factors of generalized Fermat numbers"</a>, Math. Comp. 80 (2011), pp. 1865-1866.

%o (PARI) print1(7, ", "); forprime(p=17, 274568286337, z=znorder(Mod(5/2, p)); if(2^ispower(z)==z, print1(p, ", ")));

%Y Cf. A094475, A294132, A294134, A294135, A294136.

%K nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Oct 23 2017