A010383 Squares mod 21.

0, 1, 4, 7, 9, 15, 16, 18

Offset

1,3

Links

Table of n, a(n) for n=1..8.

Mathematica

Union[PowerMod[Range[21], 2, 21]] (* Alonso del Arte, Dec 21 2019 *)

Prog

(Sage) [quadratic_residues(21)] # Zerinvary Lajos, May 24 2009
(Scala) (1 to 21).map(n => (n * n) % 21).toSet.toSeq.sorted // Alonso del Arte, Dec 21 2019

Crossrefs

Row 21 of A096008.

Cf. A028734.

Sequence in context: A032778 A282058 A210497 * A010403 A032709 A243172

Adjacent sequences: A010380 A010381 A010382 * A010384 A010385 A010386

Keyword

nonn,fini,full,easy

Author

N. J. A. Sloane

Status

approved