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 A066981 #4 Oct 30 2022 18:19:59
%S A066981 1,2,3,4,4,6,7,6,9,8,7,10,12,14,7,11,16,11,12,10,13,14,19,14,12,24,27,
%T A066981 20,10,14,19,22,17,20,13,15,28,13,24,10,19,26,33,20,17,21,15,17,37,24,
%U A066981 31,36,44,29,16,28,29,20,37,18,28,21,33,42,16,34,51,26,33,26,44,17,56
%N A066981 Number of residues of Lucas numbers modulo n.
%e A066981 a(15)=7, since Lucas numbers reduced modulo 15 are {1, 2, 3, 4, 7, 11, 14}.
%t A066981 Table[Length[Union[Mod[LucasL[Range[500]],n]]],{n,75}] (* _Harvey P. Dale_, Dec 17 2014 *)
%Y A066981 Cf. A000032, A066853.
%K A066981 nonn
%O A066981 1,2
%A A066981 _Reiner Martin_, Jan 26 2002