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 A028791 #15 Dec 26 2019 05:10:09 %S A028791 2,5,6,7,8,11,14,15,17,18,19,20,21,23,24,26,28,29,31,32,33,34,35,37, %T A028791 38,41,44,45,46,47,50,53,54,56,57,58,59,60,62,63,65,67,68,70,71,72,73, %U A028791 74,76,77 %N A028791 Nonsquares mod 78. %t A028791 Complement[Range[0, 77], PowerMod[Range[78], 2, 78]] (* _Alonso del Arte_, Dec 26 2019 *) %o A028791 (PARI) for(k=0, 78, if(!issquare(Mod(k, 78)), print1(k, ", "))) \\ _Hugo Pfoertner_, Dec 02 2019 %o A028791 (Scala) (0 to 77).diff((1 to 78).map(n => (n * n) % 78)) // _Alonso del Arte_, Dec 26 2019 %Y A028791 Cf. A010439. %K A028791 nonn,fini,full,easy %O A028791 1,1 %A A028791 _N. J. A. Sloane_ %E A028791 Incorrect term 39 removed by _Alonso del Arte_, Dec 01 2019