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 A236584 #8 Jun 13 2015 00:54:57 %S A236584 1,1,1,5,11,19,45,105,219,475,1061,2313,5027,11035,24173,52793,115499, %T A236584 252827,552981,1209545,2646419,5789563,12664925,27706873,60614235, %U A236584 132602171,290087749,634616521,1388325507,3037181147 %N A236584 The number of tilings of a 9 X (2n) floor with 2 X 3 hexominoes. %C A236584 Tilings are counted irrespective of internal symmetry: Tilings that match each other after rotations and/or reflections are counted with their multiplicity. %H A236584 R. J. Mathar, <a href="http://arxiv.org/abs/1311.6135">Paving rectangular regions...</a>, arXiv:1311.6135, Table 52. %H A236584 R. J. Mathar, <a href="http://arxiv.org/abs/1406.7788">Tilings of Rectangular Regions by Rectangular Tiles: Counts Derived from Transfer Matrices</a>, arXiv:1406.7788 [math.CO], eq. (35). %H A236584 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,4,-2). %F A236584 G.f.: (1-x)/(-4*x^3+1-2*x+x^2+2*x^4). %p A236584 g := (1-x)/(-4*x^3+1-2*x+x^2+2*x^4) ; %p A236584 taylor(%,x=0,30) ; %p A236584 gfun[seriestolist](%) ; %Y A236584 Cf. A000079 (5Xn floor), A182097 (6Xn floor), A000244 (7Xn floor), A236583 (8X3n floor) %K A236584 easy,nonn %O A236584 0,4 %A A236584 _R. J. Mathar_, Jan 29 2014