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 A251628 #7 Dec 12 2014 05:27:15 %S A251628 1,4,2,2,4,1,4,7,4,4,2,4,4,2,4,2,4,2,2,4,6,4,4,2,4,6,4,4,2,2,2,4,2,4, %T A251628 4,4,2,4,2,4,1,2,4,4,2,12,2,4,1,4,4,4,4,2,4,2,4,6,4,4,2,2,2,4,2,2,4,4, %U A251628 4,4,4,4,4,2,2,2,6,4,2,4,4 %N A251628 Number of lattice points of the Archimedean tiling (3,4,6,4) on the circles R(n) = sqrt(A249870(n) + A249871(n)* sqrt(3)) around any lattice point. First differences of A251627. %C A251628 The squares of the increasing radii of the lattice point hitting circles for the Archimedean tiling (3,4,6,4) are given in A249870 and A249871. %C A251628 See the notes given in a link under A251627. %F A251628 a(n) = A251627(n) - A251627(n-1), for n >= 1 and a(0) = 1. %e A251628 n = 4: on the circle with R(4) = sqrt(2 + sqrt(3)), approximately 1.932, around any lattice point lie a(4) = 4 points, namely in Cartesian coordinates, [+/-(1 + sqrt(3)/2), 1/2] and [+/-(1/2), -(1 + sqrt(3)/2)]. %Y A251628 Cf. A249870, A249871, A251627. %K A251628 nonn,easy %O A251628 0,2 %A A251628 _Wolfdieter Lang_, Dec 09 2014