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 A159617 #17 Jul 05 2020 13:43:13
%S A159617 1,7,64,560,4936,43456,382656,3369408,29668864,261244928,2300355072,
%T A159617 20255449088,178356473856,1570492542976,13828748541952,
%U A159617 121767076888576,1072202663100416,9441127931576320,83132508142305280,732011467286249472
%N A159617 G.f.: (1-x)/(1-8*x-8*x^2+8*x^3).
%C A159617 Number of tilings of a 2xn board with squares of 2 colors and dominoes of 2 colors if n>2. The number of tilings is 6 if n=1, and 56 if n=2.
%H A159617 Vincenzo Librandi, <a href="/A159617/b159617.txt">Table of n, a(n) for n = 0..1000</a>
%H A159617 M. Katz, C. Stenson, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL12/Stenson/stenson8.html">Tiling a 2xn-board with squares and dominoes</a>, J. Int. Seq. 12 (2009) # 09.2.2.
%H A159617 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (8,8,-8).
%F A159617 a(n) = 8*a(n-1) + 8*a(n-2) - 8*a(n-3) for n>2. - _Colin Barker_, Jul 05 2020
%t A159617 CoefficientList[Series[(1 - x)/(1 - 8 x - 8 x^2 + 8 x^3), {x, 0, 40}], x] (* _Vincenzo Librandi_, Dec 11 2012 *)
%o A159617 (PARI) Vec((1 - x) / (1 - 8*x - 8*x^2 + 8*x^3) + O(x^25)) \\ _Colin Barker_, Jul 05 2020
%Y A159617 Cf. A030186, A102436, A159616.
%K A159617 nonn,easy
%O A159617 0,2
%A A159617 _R. J. Mathar_, Apr 17 2009