A122907 Numbers m such that in Z/mZ the number of squares is greater than or equal to the number of invertible elements.

1, 2, 3, 4, 6, 10, 12, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 106, 114, 118, 122, 134, 138, 142, 146, 150, 158, 162, 166, 174, 178, 186, 194, 202, 206, 210, 214, 218, 222, 226, 242, 246, 250, 254, 258, 262, 274

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

Union of A122903 and A122905.

Complement of A122904 in positive integers.

Cf. A000010, A000224, A122906.

Programs

Mathematica

Select[Range@275, 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] = True; q[k_] := Times @@ f @@@ FactorInteger[k] >= 1; Select[Range[300], q] (* Amiram Eldar, Nov 11 2024 *)