A091495 Odd, squarefree n such that n/phi(n) > 2, where phi is Euler's totient function.

105, 165, 195, 1155, 1365, 1785, 1995, 2145, 2415, 2805, 3003, 3045, 3135, 3255, 3315, 3705, 3795, 3885, 3927, 4305, 4389, 4485, 4515, 4641, 4785, 4845, 4935, 5115, 5187, 5313, 5565, 5655, 5865, 6045, 6105, 6195, 6405, 6555, 6765, 7035, 7095, 7215

Offset

1,1

Comments

Apparently the squarefree members of the sequence A036798. Note that 105, 165 and 195 are the only terms having 3 prime factors. Also note that all the numbers listed above have 3 as a factor. The smallest number of this form not divisible by 3 is 37182145 = 5*7*11*13*17*19*23.

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Mathematica

lst={}; Do[f=FactorInteger[n]; s=Times@@Last/@f; If[s==1&&Times@@(1-1/(First/@f))<1/2, AppendTo[lst, n]], {n, 3, 10000, 2}]; lst
Select[Range[1, 7301, 2], SquareFreeQ[#]&&#/EulerPhi[#]>2&] (* Harvey P. Dale, Jul 10 2017 *)

Crossrefs

Cf. A036798.

Cf. A118700

Sequence in context: A076762 A036798 A119434 * A256673 A308779 A046405

Adjacent sequences: A091492 A091493 A091494 * A091496 A091497 A091498

Keyword

nonn

Author

T. D. Noe, Jan 15 2004

Status

approved