A122903 Numbers m such that in Z/mZ the number of squares is equal to the number of invertible elements.

1, 3, 4, 12, 70, 90, 210

Offset: 1

Author

Max Alekseyev, Sep 18 2006

Keywords

• fini
• full
• nonn

Comments

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

Crossrefs

Cf. A000010, A000224, A122904, A122905, A122906, A122907.

Programs

Mathematica

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[210], q] (* Amiram Eldar, Nov 11 2024 *)