a(n) is the largest prime factor of 2^n + 3^n.

Terms

a(0) =5a(1) =13a(2) =7a(3) =97a(4) =11a(5) =61a(6) =463a(7) =401a(8) =577a(9) =4621a(10) =35839a(11) =5521a(12) =4057a(13) =369181a(14) =241a(15) =14177a(16) =7039a(17) =181a(18) =555029a(19) =3121a(20) =92233a(21) =2414250301a(22) =13249a(23) =41432641a(24) =513101a(25) =13761229a(26) =377604937a(27) =3001769a(28) =148466603a(29) =24001