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
MATHEMATICA
Select[Range[13000], DivisorSigma[1, #]==EulerPhi[#*PrimeNu[#]-1]&] (* Harvey P. Dale, Feb 02 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 02 2002
STATUS
approved