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Numbers n such that in Z/nZ the number of squares is strictly greater than the number of invertible elements.
5

%I #9 Dec 14 2016 08:35:13

%S 2,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,66,74,78,82,86,94,98,

%T 102,106,114,118,122,134,138,142,146,150,158,162,166,174,178,186,194,

%U 202,206,214,218,222,226,242,246,250,254,258,262,274,278,282,294,298,302

%N Numbers n such that in Z/nZ the number of squares is strictly greater than the number of invertible elements.

%H Ivan Neretin, <a href="/A122905/b122905.txt">Table of n, a(n) for n = 1..10000</a>

%F n such that A000224(n) > A000010(n). Complement of A122906 in positive integers.

%t Select[Range@310, Length@Union@Mod[Range[#]^2, #] > EulerPhi[#] &] (* _Ivan Neretin_, Dec 14 2016 *)

%Y Cf. A122903, A122904, A122906, A122907.

%K nonn

%O 1,1

%A _Max Alekseyev_, Sep 18 2006