This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A010389 #17 Nov 27 2019 01:38:19 %S A010389 0,1,4,7,9,10,13,16,19,22,25 %N A010389 Squares mod 27. %t A010389 Union[PowerMod[Range[27], 2, 27]] (* _Alonso del Arte_, Nov 27 2019 *) %o A010389 (Sage) [quadratic_residues(27)] # _Zerinvary Lajos_, May 24 2009 %o A010389 (Scala) (1 to 27).map(n => n * n).map(_ % 27).toSet.toSeq.sorted // _Alonso del Arte_, Nov 27 2019 %Y A010389 Cf. A028740. %K A010389 nonn,fini,full %O A010389 1,3 %A A010389 _N. J. A. Sloane_