OFFSET
1,2
COMMENTS
Duplicate of A020488. - Peter Luschny, Aug 26 2011
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 11.
MATHEMATICA
Select[Range[500], EulerPhi[#]==DivisorSigma[0, #]&] (* Harvey P. Dale, Jun 18 2011 *)
CROSSREFS
KEYWORD
dead
AUTHOR
N. J. A. Sloane, Jan 23 2003
EXTENSIONS
Corrected by Harvey P. Dale, Jun 18 2011
STATUS
approved