New factors appearing in the factorization of 7^k - 2^k as k increases.

Terms

a(0) =5a(1) =3a(2) =67a(3) =53a(4) =11a(5) =61a(6) =13a(7) =164683a(8) =2417a(9) =163a(10) =739a(11) =1871a(12) =199a(13) =1987261a(14) =2221a(15) =1301a(16) =14894543a(17) =71a(18) =1289a(19) =31a(20) =136261a(21) =17a(22) =339121a(23) =137a(24) =443a(25) =766606297a(26) =19a(27) =2017a(29) =5329741a(30) =43