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 A028740 #11 Jul 13 2025 14:49:54 %S A028740 2,3,5,6,8,11,12,14,15,17,18,20,21,23,24,26 %N A028740 Nonsquares mod 27. %t A028740 Complement[Range[0, 26], PowerMod[Range[27], 2, 27]] (* _Alonso del Arte_, Nov 27 2019 *) %o A028740 (Scala) val squaresMod27 = (0 to 26).map(n => n * n).map(_ % 27) %o A028740 (0 to 26).diff(squaresMod27) // _Alonso del Arte_, Nov 27 2019 %Y A028740 Cf. A010389. Subsequence of A028794. %K A028740 nonn,fini,full %O A028740 1,1 %A A028740 _N. J. A. Sloane_