Largest prime factor of 5^n + 1.

Terms

a(0) =2a(1) =3a(2) =13a(3) =7a(4) =313a(5) =521a(6) =601a(7) =449a(8) =11489a(9) =5167a(10) =9161a(11) =5281a(12) =390001a(13) =38923a(14) =234750601a(15) =7621a(16) =29423041a(17) =41540861a(18) =6597973a(19) =213029a(20) =632133361a(21) =7603a(24) =152587500001a(25) =50150933101a(27) =16018507