A028767 Nonsquares mod 54.

2, 3, 5, 6, 8, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 29, 30, 32, 33, 35, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• fini
• full
• easy

Crossrefs

Cf. A010415, A028740 (subsequence).

Programs

Magma

[ n: n in [0..53] | not IsSquare(R! n) where R:= ResidueClassRing(54)]; // Vincenzo Librandi, Dec 28 2019

Mathematica

Complement[Range[0, 53], PowerMod[Range[54], 2, 54]] (* Alonso del Arte, Dec 27 2019 *)

Scala

(0 to 53).diff((1 to 54).map(n => (n * n) % 54)) // Alonso del Arte, Dec 27 2019