%I #17 Dec 23 2019 06:07:04
%S 0,1,3,4,6,9,12,13,16,18,24,25,27,31,36,39,46,48,49,52,54,55,58,64
%N Squares mod 69.
%t Union[PowerMod[Range[69], 2, 69]] (* _Alonso del Arte_, Dec 23 2019 *)
%o (Sage) [quadratic_residues(69)] # _Zerinvary Lajos_, May 24 2009
%o (Scala) (1 to 69).map(n => (n * n) % 69).toSet.toSeq.sorted // _Alonso del Arte_, Dec 23 2019
%Y Cf. A028782.
%K nonn,fini,full,easy
%O 1,3
%A _N. J. A. Sloane_