Largest prime factor of 4^(2*n+1)+1.

Terms

a(0) =5a(1) =13a(2) =41a(3) =113a(4) =109a(5) =2113a(6) =1613a(7) =1321a(8) =26317a(9) =525313a(10) =14449a(11) =30269a(12) =268501a(13) =279073a(14) =536903681a(15) =384773a(16) =4327489a(17) =47392381a(18) =231769777a(19) =21841a(20) =43249589a(22) =29247661a(25) =1326700741