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Squares mod 18.
1

%I #20 Dec 18 2019 21:51:53

%S 0,1,4,7,9,10,13,16

%N Squares mod 18.

%t Union[PowerMod[Range[18], 2, 18]] (* _Alonso del Arte_, Dec 18 2019 *)

%o (Sage) [quadratic_residues(18)] # _Zerinvary Lajos_, May 24 2009

%o (Scala) (1 to 18).map(n => (n * n) % 18).toSet.toSeq.sorted // _Alonso del Arte_, Dec 18 2019

%Y Row 18 of A096008.

%Y Cf. A028731.

%K nonn,fini,full

%O 1,3

%A _N. J. A. Sloane_