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 A078100 #24 Sep 08 2022 08:45:08
%S A078100 4,27,187,1302,9075,63267,441090,3075255,21440547,149482638,
%T A078100 1042187067,7266087315,50658875658,353191693599,2462438631411,
%U A078100 17168025532662,119694800484387,834507453158019,5818153224352338,40563936024707079,282810170576026755
%N A078100 1/6 of the number of ways of 3-coloring a 4 X n grid.
%C A078100 Also the number of 3-colorings of the P_4 X P_n grid graph up to permutation of the colors. - _Andrew Howroyd_, Jun 26 2017
%D A078100 Michael S. Paterson (Warwick), personal communication.
%H A078100 Alois P. Heinz, <a href="/A078100/b078100.txt">Table of n, a(n) for n = 1..1000</a>
%H A078100 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-15,6).
%F A078100 See A078099 for formula.
%F A078100 G.f.: x*(9*x-4-4*x^2) / (6*x^3-15*x^2+9*x-1). - _Alois P. Heinz_, Mar 23 2009
%p A078100 a:= n-> (Matrix([[27, 4, 2/3]]). Matrix([[9, 1, 0], [ -15, 0, 1], [6, 0, 0]])^n)[1, 3]: seq(a(n), n=1..30); # _Alois P. Heinz_, Mar 23 2009
%t A078100 LinearRecurrence[{9, -15, 6}, {4, 27, 187}, 21] (* _Jean-François Alcover_, Feb 13 2016 *)
%o A078100 (Magma) I:=[4,27,187]; [n le 3 select I[n] else 9*Self(n-1)-15*Self(n-2)+6*Self(n-3): n in [1..30]]; // _Vincenzo Librandi_, Feb 13 2016
%Y A078100 Row 4 of (1/2)*A078099.
%Y A078100 Row 4 of A207997.
%K A078100 nonn,easy
%O A078100 1,1
%A A078100 _N. J. A. Sloane_, Dec 05 2002
%E A078100 More terms from _Alois P. Heinz_, Mar 23 2009
%E A078100 Name clarified by _Andrew Howroyd_, Jun 26 2017