S000364


Numbers n such that 7^n-1 has only one primitive prime factor.

2, 3, 4, 5, 6, 8, 13, 18, 21, 28, 30, 34, 36, 46, 48, 50, 54, 55, 58, 63, 76, 84, 94, 105, 122, 131, 148, 149, 224, 280, 288, 296, 332, 352, 456, 528, 531, 581, 650, 654, 730, 740, 759, 1026, 1047, 1065, 1460, 1660, 1699, 1959, 2067, 2260, 2380, 2665, 2890

1

S000364

Numbers n such that S000005(n) = 1.

T. D. Noe, Plot of 69 terms

T. D. Noe, Table of 69 terms

Eric W. Weisstein, MathWorld: Primitive Prime Factor

(Mma) d = 7; Select[Range[1000], PrimePowerQ[Cyclotomic[#, d]/GCD[Cyclotomic[#, d], #]] &]

Cf. A161508 (2^n-1 case), S000005S000360-S000366.

nonn,hard

T. D. Noe, Nov 20 2014

© Tony D Noe 2014-2015