A217301 Numbers n such that gcd(n, phi(n)) = gcd(phi(n), sigma(n)) = gcd(sigma(n), n) = tau(n).

1, 184, 376, 1336, 1912, 2104, 2872, 3064, 3832, 4024, 4792, 5176, 5752, 5944, 6712, 6904, 7096, 7864, 8824, 9784, 10552, 10936, 11512, 11896, 12472, 12664, 12856, 14584, 14776, 16312, 16504, 16696, 17656, 19192, 19384, 19576, 20344, 21304, 21496, 22644

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[20000], GCD[#, EulerPhi[#]] ==  GCD[EulerPhi[#], DivisorSigma[1, #]] == GCD[#, DivisorSigma[1, #]] == DivisorSigma[0, #] &] (* Jean-François Alcover, Mar 18 2013 *)

Crossrefs

Cf. A069810.

Sequence in context: A171563 A347504 A061657 * A351278 A239457 A235258

Adjacent sequences: A217298 A217299 A217300 * A217302 A217303 A217304

Keyword

nonn,easy

Author

Jayanta Basu, Mar 17 2013

Status

approved