OFFSET
2,1
EXAMPLE
tau(50) = number of divisors of 50 = 6; phi(sum of prime factors of 50) = phi(2 + 5) = 6. Hence 50 is a term of the sequence.
MATHEMATICA
Select[Range[2, 10^3], EulerPhi[Apply[Plus, Transpose[FactorInteger[ # ]][[1]]]] == DivisorSigma[0, # ] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Oct 15 2002
STATUS
approved