OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[1000], Divisible[DivisorSigma[1, #], EulerPhi[1 + #]] &] (* David Nacin, Mar 01 2012 *)
PROG
(PARI) is(n)=!(sigma(n)%eulerphi(n+1)) \\ Charles R Greathouse IV, Sep 25 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Definition corrected by David Nacin, Mar 01 2012
STATUS
approved