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A116045 n+phi(n)+phi(phi(n)) is a prime. 1
1, 4, 5, 9, 13, 17, 19, 21, 25, 33, 35, 39, 41, 43, 49, 61, 75, 79, 85, 87, 95, 101, 121, 133, 137, 141, 153, 155, 159, 163, 165, 169, 177, 181, 193, 199, 201, 203, 207, 213, 215, 231, 233, 245, 251, 257, 259, 265, 267, 271, 277, 291, 299, 307, 309, 337, 339 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

EXAMPLE

13+phi(13)+phi(phi(13)) = 29.

MATHEMATICA

epQ[n_]:=Module[{ep=EulerPhi[n]}, PrimeQ[n+ep+EulerPhi[ep]]]

Select[Range[400], epQ]  (* From Harvey P. Dale, Mar 6 2011 *)

CROSSREFS

Cf. A068080.

Sequence in context: A034705 A006844 A022425 * A096818 A038099 A120740

Adjacent sequences:  A116042 A116043 A116044 * A116046 A116047 A116048

KEYWORD

nonn

AUTHOR

Giovanni Resta (g.resta(AT)iit.cnr.it), Feb 13 2006

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Last modified February 15 17:13 EST 2012. Contains 205828 sequences.