Numbers n such that 8^n-1 has only one primitive prime factor.
1, 2, 3, 6, 9, 18, 30, 42, 78, 87, 114, 138, 189, 303, 318, 330, 408, 462, 504, 561, 1002, 1389, 1746, 1794, 2040, 2418, 2790, 3894, 4077, 4722, 6738
1
Numbers n such that S000006(n) = 1.
T. D. Noe, Plot of 31 terms
T. D. Noe, Table of 31 terms
Eric W. Weisstein, MathWorld: Primitive Prime Factor
(Mma) d = 8; Select[Range[1000], PrimePowerQ[Cyclotomic[#, d]/GCD[Cyclotomic[#, d], #]] &]
Cf. A161508 (2^n-1 case), S000006, S000360-S000366.
nonn,hard,more
T. D. Noe, Nov 20 2014