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 A265046 #15 Jan 01 2016 17:19:54
%S A265046 1,3,5,8,13,18,23,28,32,36,40,44,48,52,56,60,64,68,72,76,80,84,88,92,
%T A265046 96,100,104,108,112,116,120,124,128,132,136,140,144,148,152,156,160,
%U A265046 164,168,172,176,180,184,188,192,196,200,204,208,212,216,220,224,228,232
%N A265046 Coordination sequence for a 4.6.6 point in the 3-transitive tiling {4.6.6, 6.6.6, 6.6.6.6} of the plane by squares and dominoes (hexagons).
%C A265046 This tiling is 3-transitive but not 3-uniform since the polygons are not regular. It is a common floor-tiling.
%C A265046 The coordination sequences with respect to the points of types 4.6.6 (labeled "C" in the illustration), 6.6.6 ("B"), 6.6.6.6 ("A") are A265046, A265045, and A008574, respectively. The present sequence is for a "C" point.
%H A265046 Colin Barker, <a href="/A265046/b265046.txt">Table of n, a(n) for n = 0..1000</a>
%H A265046 N. J. A. Sloane, <a href="/A265045/a265045.png">A portion of the 3-transitive tiling {4.6.6, 6.6.6, 6.6.6.6}</a>
%H A265046 N. J. A. Sloane, <a href="/A265045/a265045_1.png">A portion of the 3-transitive tiling {4.6.6, 6.6.6, 6.6.6.6} showing the three types of point</a>
%H A265046 N. J. A. Sloane, <a href="/A265046/a265046.png">Hand-drawn illustration showing a(0) to a(8)</a>
%H A265046 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A265046 For n >= 7 all three sequences equal 4n. (For n >= 7 the n-th shell contains n-1 points in the interior of each quadrant plus 4 points on the axes.)
%F A265046 From _Colin Barker_, Jan 01 2016: (Start)
%F A265046 a(n) = 2*a(n-1)-a(n-2) for n>8.
%F A265046 a(n) = 4*n for n>6.
%F A265046 G.f.: (1+x)*(1+x^3+x^4-x^5+x^6-x^7) / (1-x)^2.
%F A265046 (End)
%o A265046 (PARI) Vec((1+x)*(1+x^3+x^4-x^5+x^6-x^7)/(1-x)^2+ O(x^100)) \\ _Colin Barker_, Jan 01 2016
%Y A265046 Cf. A008574, A265045.
%K A265046 nonn,easy
%O A265046 0,2
%A A265046 _N. J. A. Sloane_ and _Susanna Cuyler_, Dec 27 2015