A066994 Numbers n such that phi(n) divides n*sigma(n).

1, 2, 3, 4, 6, 8, 10, 12, 14, 15, 16, 18, 20, 21, 24, 26, 27, 30, 32, 35, 36, 39, 40, 42, 48, 54, 55, 56, 60, 63, 64, 70, 72, 78, 80, 84, 88, 96, 98, 104, 105, 108, 110, 114, 116, 120, 125, 126, 128, 135, 140, 144, 147, 150, 155, 156, 160, 162, 165, 168, 189, 190, 192

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[200], Divisible[# DivisorSigma[1, #], EulerPhi[#]]&] (* Harvey P. Dale, Aug 23 2019 *)

Prog

(PARI) { n=0; for (m=1, 10^10, if ((m*sigma(m)) % eulerphi(m) == 0 , write("b066994.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Apr 23 2010

Crossrefs

Cf. A011775.

Sequence in context: A284038 A285302 A026281 * A081000 A336367 A064377

Adjacent sequences: A066991 A066992 A066993 * A066995 A066996 A066997

Keyword

nonn

Author

Benoit Cloitre, Jan 27 2002

Extensions

Missing term a(7)=10 added by Harry J. Smith, Apr 23 2010

Status

approved