A173929 - OEIS

%I #3 Sep 08 2022 08:45:51

%S 2,5,7,19,13,71,97,181,3691,2521,191861,489061,6811741,138907099,

%T 708158977,1321442641,26947261171,18405321661,

%U 381765135195632792959100810331957408101589361

%N Primes in A173299.

%C a(20) has 84 digits. Most terms of A173299 are nonprime.

%o (Magma) Z<x>:=PolynomialRing(Integers()); N<r>:=NumberField(2*x^2-2*x-1); S:=[ r^n+(1-r)^n: n in [1..300] ]; [ k: j in [1..#S] | IsPrime(k) where k is Numerator(RationalField()!S[j])];

%Y Cf. A173299.

%K nonn

%O 1,1

%A _Klaus Brockhaus_, Mar 02 2010