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!)
A122906 Numbers n such that in Z/nZ the number of squares is less than or equal to the number of invertible elements. 6

%I #11 Sep 24 2018 16:53:14

%S 1,3,4,5,7,8,9,11,12,13,15,16,17,19,20,21,23,24,25,27,28,29,31,32,33,

%T 35,36,37,39,40,41,43,44,45,47,48,49,51,52,53,55,56,57,59,60,61,63,64,

%U 65,67,68,69,70,71,72,73,75,76,77,79,80,81,83,84,85,87,88,89,90,91,92,93

%N Numbers n such that in Z/nZ the number of squares is less than or equal to the number of invertible elements.

%C The terms 70 and 90 show that sequence is strictly different from A042965. - _Andrew S. Plewe_, Jun 13 2007

%H Ivan Neretin, <a href="/A122906/b122906.txt">Table of n, a(n) for n = 1..10000</a>

%F Numbers n such that A000224(n) <= A000010(n). Union of A122903 and A122904. Complement of A122905 in positive integers.

%t Select[Range@94, Length@Union@Mod[Range[#]^2, #] <= EulerPhi[#] &] (* _Ivan Neretin_, Dec 14 2016 *)

%Y Cf. A122903, A122904, A122905, A122907.

%K nonn

%O 1,2

%A _Max Alekseyev_, Sep 18 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 March 28 16:12 EDT 2024. Contains 371254 sequences. (Running on oeis4.)