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 A136691 #7 May 08 2014 18:10:46
%S A136691 1,1,2,2,2,2,1,3,2,2,3,1,3,3,2,2,2,2,3,1,1,1,2,2,3,3,2,2,2,2,1,3,2,2,
%T A136691 3,1,1,1,2,2,1,1,2,2,2,2,3,1,3,3,2,2,2,2,3,1,2,2,3,1,3,3,2,2,2,2,3,1,
%U A136691 1,1,2,2,1,1,2,2,2,2,3,1,1,1,2,2,2,2,1,3,2,2,1,3,1,1,2,2,3,3,2,2
%N A136691 Final nonzero digit of n! in base 4.
%H A136691 Harvey P. Dale, <a href="/A136691/b136691.txt">Table of n, a(n) for n = 0..1000</a>
%e A136691 6! = 720 decimal = 23100 quartal, so a(6) = 1.
%t A136691 nzd[n_]:=Module[{rd=RealDigits[n!,4][[1]]},If[Last[rd]!=0,Last[rd], Last[ Flatten[Most[Split[rd]]]]]]; Array[nzd,100,0] (* _Harvey P. Dale_, May 08 2014 *)
%Y A136691 Cf. A000142, A136690, A136692, A136693, A136694, A136695, A136696, A008904, A136697, A136698, A136699, A136700, A136701, A136702.
%K A136691 base,easy,nonn
%O A136691 0,3
%A A136691 _Carl R. White_, Jan 16 2008