A070809 Cototient(totient(n))=A070556(n) is not a power of 2 and n is not a prime number.

1, 22, 25, 27, 33, 38, 44, 46, 49, 50, 54, 55, 57, 62, 63, 66, 69, 74, 75, 76, 77, 81, 82, 86, 88, 91, 92, 93, 94, 95, 98, 99, 100, 106, 108, 110, 111, 114, 115, 117, 118, 121, 122, 123, 124, 125, 126, 129, 132, 133, 134, 135, 138, 141, 142, 143, 146, 147, 148

Offset

1,2

Links

Table of n, a(n) for n=1..59.

Example

n=95: Phi[95]=72,cototient[72]=72-phi[72]=72-24-=48 is not a power of 2.

Mathematica

Do[s= EulerPhi[n]-EulerPhi[EulerPhi[n]]; If[ !IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 1000}]

Crossrefs

Cf. A070556, A051953, A054571, A070806, A070807, A070810, A070811.

Sequence in context: A092631 A061371 A254753 * A280646 A345479 A295799

Adjacent sequences: A070806 A070807 A070808 * A070810 A070811 A070812

Keyword

nonn

Author

Labos Elemer, May 08 2002

Status

approved