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 A094920 #13 May 19 2020 19:13:09
%S A094920 0,0,1,0,1,0,1,0,4,6,1,0,1,6,1,0,1,0,1,16,10,6,1,0,6,6,13,16,1,6,1,0,
%T A094920 31,6,11,0,1,6,31,16,1,0,1,24,31,6,1,0,29,6,31,0,1,0,11,48,31,6,1,36,
%U A094920 1,6,31,0,1,12,1,20,31,16,1,0,1,6,31,4,39,6,1,16,40,6,1,0,16,6,31,64,1,36,57,64
%N A094920 a(n) = (5^n-1)/4 mod n.
%H A094920 Antti Karttunen, <a href="/A094920/b094920.txt">Table of n, a(n) for n = 1..16384</a>
%H A094920 Antti Karttunen, <a href="/A094920/a094920.txt">Data supplement: n, a(n) computed for n = 1..65537</a>
%t A094920 Table[Mod[(5^n-1)/4,n],{n,100}] (* _Harvey P. Dale_, Sep 20 2016 *)
%o A094920 (PARI) A094920(n) = lift(Mod((5^n-1)/4,n)); \\ _Antti Karttunen_, May 19 2020
%Y A094920 Cf. A003463.
%K A094920 nonn
%O A094920 1,9
%A A094920 _N. J. A. Sloane_, Jun 18 2004