S000374


Numbers n such that 9^n+1 has only one primitive prime factor.

0, 1, 2, 3, 5, 6, 8, 9, 10, 15, 16, 18, 27, 32, 33, 59, 69, 76, 91, 116, 132, 168, 170, 190, 207, 223, 246, 270, 312, 360, 381, 533, 547, 549, 585, 615, 627, 660, 714, 773, 1009, 1287, 1362, 1402, 1460, 1537, 1658, 1823, 2062, 2066, 2093, 2310, 2401, 2733

1

S000374

Numbers n such that S000014(n) = 1.

T. D. Noe, Plot of 63 terms

T. D. Noe, Table of 63 terms

Eric W. Weisstein, MathWorld: Primitive Prime Factor

(Mma) d = 9; f2[n_] := Cyclotomic[2*n, d]/Cyclotomic[n, d]; Join[{0}, Select[Range[1000], PrimePowerQ[f2[#]/GCD[f2[#], #]] &]]

Cf. S000014.

nonn,hard

T. D. Noe, Nov 21 2014

© Tony D Noe 2014-2015