A116000 phi(n) + sigma(n) gives a semiprime (A001358).

2, 3, 4, 5, 6, 7, 10, 11, 13, 16, 17, 19, 22, 23, 25, 27, 29, 31, 37, 40, 41, 43, 46, 47, 52, 53, 58, 59, 61, 64, 67, 68, 71, 72, 73, 79, 80, 82, 83, 89, 97, 98, 101, 103, 106, 107, 109, 113, 117, 127, 128, 131, 136, 137, 139, 144, 149, 151, 157, 162, 163, 166, 167

Offset

1,1

Links

Table of n, a(n) for n=1..63.

Example

phi(101)+sigma(101)=202=2*101.

Mathematica

Select[Range[200], PrimeOmega[EulerPhi[#]+DivisorSigma[1, #]]==2&] (* Harvey P. Dale, Feb 05 2013 *)

Crossrefs

Cf. A001358, A116016, A116001.

Sequence in context: A064295 A001751 A191927 * A251595 A050725 A080571

Adjacent sequences: A115997 A115998 A115999 * A116001 A116002 A116003

Keyword

nonn

Author

Giovanni Resta, Feb 13 2006

Status

approved