A028727 Nonsquares mod 14.

3, 5, 6, 10, 12, 13

Offset

1,1

Links

Table of n, a(n) for n=1..6.

Example

Since 6 is not a perfect square and there are no solutions to x^2 = 6 mod 14 in integers, 6 is in the sequence.
Although 7 is not a perfect square either, there are solutions to x^2 = 7 mod 14, namely odd multiples of 7. Thus 7 is not in the sequence.

Mathematica

Complement[Range[0, 13], PowerMod[Range[14], 2, 14]] (* Alonso del Arte, Dec 14 2019 *)

Prog

(Scala) (0 to 13).diff((1 to 14).map(n => (n * n) % 14)) // Alonso del Arte, Dec 14 2019

Crossrefs

Cf. A010377.

Sequence in context: A187126 A065873 A072282 * A257346 A047327 A028927

Adjacent sequences: A028724 A028725 A028726 * A028728 A028729 A028730

Keyword

nonn,fini,full

Author

N. J. A. Sloane

Extensions

Incorrect term 7 removed by Alonso del Arte, Dec 14 2019

Status

approved