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 A192452 #9 Mar 14 2015 11:40:50 %S A192452 3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20,21,22,23,24,25,26,27,28, %T A192452 29,30,31,32,33,35,36,37,38,39,40,42,43,44,45,46,47,48,49,50,51,52,53, %U A192452 54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71 %N A192452 Numbers n such that -1 is not a 4th power mod n. %C A192452 Complement of A192453. %t A192452 Table[If[Reduce[x^4==-1,Modulus->n]===False,n],{n,2,300}]//Union %K A192452 nonn %O A192452 1,1 %A A192452 _José María Grau Ribas_, Jul 01 2011