A015793 Numbers n such that phi(n) + 4 divides sigma(n).

6, 15, 21, 24, 30, 33, 39, 42, 51, 57, 66, 69, 78, 84, 87, 93, 96, 102, 108, 111, 114, 120, 123, 129, 138, 141, 159, 174, 175, 177, 183, 186, 201, 213, 219, 220, 222, 237, 246, 249, 258, 267, 282, 291, 303, 309, 318, 321, 327, 339, 350, 354, 366

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1300

Mathematica

Select[Range[400], Divisible[DivisorSigma[1, #], EulerPhi[#]+4]&] (* Harvey P. Dale, Aug 05 2014 *)

Prog

(PARI) is(n)=!(sigma(n)%eulerphi(n+4)) \\ Charles R Greathouse IV, Sep 25 2012

Crossrefs

Sequence in context: A012412 A009092 A330205 * A261078 A063466 A138109

Adjacent sequences: A015790 A015791 A015792 * A015794 A015795 A015796

Keyword

nonn

Author

Robert G. Wilson v

Status

approved