OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
filter:= n -> not isprime(n) and numtheory:-phi(n) mod numtheory:-tau(n)=0:
select(filter, [$4..1000]); # Robert Israel, Jan 05 2018
MATHEMATICA
nn=200; Rest[Select[Complement[Range[nn], Prime[Range[PrimePi[nn]]]], Divisible[ EulerPhi[#], DivisorSigma[0, #]]&]] (* Harvey P. Dale, Mar 31 2011 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 13 2002
STATUS
approved