1,1

Donovan Johnson, Table of n, a(n) for n = 1..500

sigma(15) = 24 = phi(3 * 15), so 15 is a term of the sequence.

Select[ Range[1936556], EulerPhi[3# ] == DivisorSigma[1, # ] &]

(PARI) is(n)=sigma(n)==eulerphi(3*n) \\ Charles R Greathouse IV, Dec 09 2013

Sequence in context: A027442 A208728 A219689 * A328213 A271733 A280883

Adjacent sequences: A074888 A074889 A074890 * A074892 A074893 A074894

nonn

Joseph L. Pe, Sep 13 2002

Edited and extended by Robert G. Wilson v, Sep 17 2002

approved