A122905 Numbers m such that in Z/mZ the number of squares is strictly greater than the number of invertible elements.

2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 74, 78, 82, 86, 94, 98, 102, 106, 114, 118, 122, 134, 138, 142, 146, 150, 158, 162, 166, 174, 178, 186, 194, 202, 206, 214, 218, 222, 226, 242, 246, 250, 254, 258, 262, 274, 278, 282, 294, 298, 302

Offset: 1

Author

Max Alekseyev, Sep 18 2006

Keywords

• nonn

Comments

Numbers m such that A000224(m) > A000010(m).

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Complement of A122906 in positive integers.

Cf. A000010, A000224, A122903, A122904, A122907.

Programs

Mathematica

Select[Range@310, Length@Union@Mod[Range[#]^2, #] > EulerPhi[#] &] (* Ivan Neretin, Dec 14 2016 *)
f1[p_, e_] := Floor[p^(e+1)/(2p + 2)] + 1; f1[2, e_] := Floor[2^e/6] + 2; f[p_, e_] := f1[p, e]/((p-1) * p^(e-1)); q[1] = False; q[k_] := Times @@ f @@@ FactorInteger[k] > 1; Select[Range[300], q] (* Amiram Eldar, Nov 11 2024 *)