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A116043 n+phi(n)+phi(phi(n)) is a square. 4
2, 6, 10, 11, 22, 24, 40, 62, 73, 88, 93, 96, 97, 105, 116, 127, 157, 160, 188, 228, 229, 237, 248, 292, 293, 301, 332, 352, 384, 401, 449, 464, 484, 541, 580, 640, 752, 837, 912, 945, 992, 1033, 1168, 1297, 1328, 1408, 1477, 1536, 1697, 1785, 1856, 1881 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

401+phi(401)+phi(phi(401)) = 961 = 31^2.

MATHEMATICA

epQ[n_]:=Module[{epn=EulerPhi[n]}, IntegerQ[Sqrt[n+epn+EulerPhi[ epn]]]]; Select[Range[2000], epQ] (* Harvey P. Dale, Oct 03 2011 *)

CROSSREFS

Cf. A116040, A116041, A116042.

Sequence in context: A050425 A030405 A125241 * A085258 A133520 A099017

Adjacent sequences:  A116040 A116041 A116042 * A116044 A116045 A116046

KEYWORD

nonn

AUTHOR

Giovanni Resta, Feb 13 2006

STATUS

approved

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Last modified September 20 04:04 EDT 2020. Contains 337264 sequences. (Running on oeis4.)