This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A173929 #3 Sep 08 2022 08:45:51 %S A173929 2,5,7,19,13,71,97,181,3691,2521,191861,489061,6811741,138907099, %T A173929 708158977,1321442641,26947261171,18405321661, %U A173929 381765135195632792959100810331957408101589361 %N A173929 Primes in A173299. %C A173929 a(20) has 84 digits. Most terms of A173299 are nonprime. %o A173929 (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 A173929 Cf. A173299. %K A173929 nonn %O A173929 1,1 %A A173929 _Klaus Brockhaus_, Mar 02 2010