S000360


Numbers n such that 3^n-1 has only one primitive prime factor.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 20, 21, 24, 26, 32, 33, 36, 40, 46, 60, 63, 64, 70, 71, 72, 86, 103, 108, 128, 130, 132, 143, 145, 154, 161, 236, 255, 261, 276, 279, 287, 304, 364, 430, 464, 513, 528, 541, 562, 665, 672, 680, 707, 718, 747, 760

1

S000360

Numbers n such that S000001(n) = 1.

T. D. Noe, Plot of 130 terms

T. D. Noe, Table of 130 terms

Eric W. Weisstein, MathWorld: Primitive Prime Factor

(Mma) d = 3; Select[Range[1000], PrimePowerQ[Cyclotomic[#, d]/GCD[Cyclotomic[#, d], #]] &]

Cf. A161508 (2^n-1 case), S000001S000361-S000366.

nonn,hard

T. D. Noe, Nov 20 2014

© Tony D Noe 2014-2015