A122904 Numbers m such that in Z/mZ the number of squares is strictly less than the number of invertible elements.

5, 7, 8, 9, 11, 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, 71, 72, 73, 75, 76, 77, 79, 80, 81, 83, 84, 85, 87, 88, 89, 91, 92, 93, 95, 96, 97, 99, 100

Offset

1,1

Comments

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

Links

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

Mathematica

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

Crossrefs

Cf. A000010, A000224, A122903, A122905, A122906, A122907.

Sequence in context: A171097 A166460 A118742 * A104693 A373992 A225648

Adjacent sequences: A122901 A122902 A122903 * A122905 A122906 A122907

Keyword

nonn

Author

Max Alekseyev, Sep 18 2006

Status

approved