A082954 Numbers k such that phi(k*sigma(k)) = phi(k)^2.

1, 3, 39, 111, 175, 183, 219, 333, 459, 471, 549, 579, 657, 831, 939, 969, 1191, 1263, 1371, 1413, 1443, 1623, 1737, 1839, 1983, 2019, 2199, 2271, 2379, 2493, 2631, 2817, 2847, 2907, 2991, 3279, 3459, 3573, 3603, 3639, 3711, 3789, 3963, 4113, 4131, 4143

Offset: 1

Author

Benoit Cloitre, May 26 2003

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A000203, A127473.

Programs

Mathematica

Select[Range[5000],EulerPhi[#*DivisorSigma[1,#]]==EulerPhi[#]^2&] (* Harvey P. Dale, Jan 25 2013 *)