A067878 Numbers n such that sigma(n)=phi(n*omega(n)-1).

1, 10, 33, 46, 65, 77, 123, 136, 221, 371, 385, 423, 513, 532, 545, 572, 660, 702, 753, 1248, 1566, 1643, 1720, 2033, 2635, 3243, 4533, 4798, 5177, 5346, 5495, 5605, 6460, 7463, 7565, 7683, 7739, 8201, 9342, 9741, 10780, 10792, 11679, 11880, 12256

Offset

1,2

Comments

Omega(n) refers to unique prime factors of n, i.e., prime factors taken without multiplicity. - Harvey P. Dale, Feb 02 2015

Links

Table of n, a(n) for n=1..45.

Mathematica

Select[Range[13000], DivisorSigma[1, #]==EulerPhi[#*PrimeNu[#]-1]&] (* Harvey P. Dale, Feb 02 2015 *)

Crossrefs

Sequence in context: A137723 A256352 A255533 * A067877 A367031 A348427

Adjacent sequences: A067875 A067876 A067877 * A067879 A067880 A067881

Keyword

easy,nonn

Author

Benoit Cloitre, Mar 02 2002

Status

approved