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 A003561 #10 Oct 22 2023 16:45:59 %S A003561 1,5,4,3,2,3,6,10,11,16,6,15,10,5,9,27,21,12,8,25,26,36,14,55,3,65,16, %T A003561 23,36,75,4,33,41,18,20,15,6,19,42,11,51,35,18,16,56,30,29,20,20,25, %U A003561 64,21,18,27,22,70,20,96,36,21,48,155,39,53,27,165,12,15 %N A003561 Least number m such that 5^m == +- 1 (mod 5n + 1). %K A003561 nonn %O A003561 1,2 %A A003561 _N. J. A. Sloane_