Numbers k that divide 4^k + 1, k not a power of 5.

Terms

a(0) =205a(1) =1025a(2) =2525a(3) =5125a(4) =8405a(5) =12625a(6) =25625a(7) =42025a(8) =63125a(9) =103525a(10) =128125a(11) =168305a(12) =202525a(13) =210125a(14) =255025a(15) =315625a(16) =344605a(17) =517625a(18) =640625a(19) =841525a(20) =875125a(21) =1012625a(22) =1050625a(23) =1275125a(24) =1578125a(25) =1723025a(26) =2042725a(27) =2084645