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A116000 phi(n) + sigma(n) gives a semiprime (A001358). 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 1 15:00 EST 2023. Contains 359993 sequences. (Running on oeis4.)