1,3
Table of n, a(n) for n=1..8.
Union[PowerMod[Range[28], 2, 28]] (* Alonso del Arte, Nov 28 2019 *)
(Sage) [quadratic_residues(28)] # Zerinvary Lajos, May 24 2009
(Scala) (1 to 28).map(n => n * n).map(_ % 28).toSet.toSeq.sorted // Alonso del Arte, Nov 28 2019
Cf. A028741.
Sequence in context: A134344 A324278 A119315 * A003624 A280387 A243180
Adjacent sequences: A010387 A010388 A010389 * A010391 A010392 A010393
nonn,fini,full
N. J. A. Sloane
approved
