A122906 Numbers m such that in Z/mZ the number of squares is less than or equal to the number of invertible elements.

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, 35, 36, 37, 39, 40, 41, 43, 44, 45, 47, 48, 49, 51, 52, 53, 55, 56, 57, 59, 60, 61, 63, 64, 65, 67, 68, 69, 70, 71, 72, 73, 75, 76, 77, 79, 80, 81, 83, 84, 85, 87, 88, 89, 90, 91, 92, 93

Offset

1,2

Comments

Numbers m such that A000224(m) <= A000010(m).

The terms 70 and 90 show that sequence is strictly different from A042965. - Andrew S. Plewe, Jun 13 2007

Links

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

Mathematica

Select[Range@94, 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[100], q] (* Amiram Eldar, Nov 11 2024 *)

Crossrefs

Union of A122903 and A122904.

Complement of A122905 in positive integers.

Cf. A000010, A000224, A122907.

Sequence in context: A284679 A183147 A074227 * A042965 A348004 A260003

Adjacent sequences: A122903 A122904 A122905 * A122907 A122908 A122909

Keyword

nonn

Author

Max Alekseyev, Sep 18 2006

Status

approved