Numbers k that divide 6^k-1.

Terms

a(0) =1a(1) =5a(2) =25a(3) =125a(4) =625a(5) =1555a(6) =3125a(7) =7775a(8) =15625a(9) =38875a(10) =78125a(11) =194375a(12) =390625a(13) =483605a(14) =971875a(15) =1953125a(16) =2418025a(17) =4859375a(18) =9673655a(19) =9765625a(20) =12090125a(21) =24296875a(22) =48368275a(23) =48828125a(24) =60450625a(25) =120909025a(26) =121484375a(27) =150401155a(28) =241841375