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 A028744 #10 Dec 31 2019 06:47:10 %S A028744 3,6,11,12,13,15,17,21,22,23,24,26,27,29,30 %N A028744 Nonsquares mod 31. %t A028744 Complement[Range[0, 30], PowerMod[Range[31], 2, 31]] (* _Alonso del Arte_, Dec 31 2019 *) %o A028744 (Scala) (0 to 30).diff((1 to 31).map(n => n * n % 31)) // _Alonso del Arte_, Dec 31 2019 %Y A028744 Cf. A010392. %K A028744 nonn,fini,full,easy %O A028744 1,1 %A A028744 _N. J. A. Sloane_