New factors appearing in the factorization of 5^k - 2^k as k increases.

Terms

a(0) =3a(1) =7a(2) =13a(3) =29a(4) =1031a(5) =19a(6) =25999a(7) =641a(8) =5563a(9) =11a(10) =41a(11) =1409a(12) =11551a(13) =541a(14) =406898311a(15) =1597a(16) =31a(17) =8161a(18) =17a(19) =22993a(20) =82009a(21) =3101039a(22) =37a(23) =397a(25) =61a(26) =5521a(27) =43a(28) =1009a(29) =3613a(30) =23