login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A116043 n+phi(n)+phi(phi(n)) is a square. 4

%I

%S 2,6,10,11,22,24,40,62,73,88,93,96,97,105,116,127,157,160,188,228,229,

%T 237,248,292,293,301,332,352,384,401,449,464,484,541,580,640,752,837,

%U 912,945,992,1033,1168,1297,1328,1408,1477,1536,1697,1785,1856,1881

%N n+phi(n)+phi(phi(n)) is a square.

%H Harvey P. Dale, <a href="/A116043/b116043.txt">Table of n, a(n) for n = 1..1000</a>

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

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

%Y Cf. A116040, A116041, A116042.

%K nonn

%O 1,1

%A _Giovanni Resta_, Feb 13 2006

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 17 08:02 EDT 2022. Contains 356184 sequences. (Running on oeis4.)