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 A102762 #34 Feb 25 2018 20:48:04
%S A102762 -1,2,2,3,6,11,18,27,38,51,66,83,102,123,146,171,198,227,258,291,326,
%T A102762 363,402,443,486,531,578,627,678,731,786,843,902,963,1026,1091,1158,
%U A102762 1227,1298,1371,1446,1523,1602,1683,1766,1851,1938,2027,2118,2211,2306,2403,2502,2603,2706,2811,2918,3027,3138,3251,3366
%N A102762 Curvatures of (largest) kissing circles along the circumference, starting with curvature = -1 and 2.
%C A102762 A059100 has a totally different description but is the same sequence (omitting the first two numbers here)
%H A102762 Andrew Howroyd, <a href="/A102762/b102762.txt">Table of n, a(n) for n = 0..1000</a>
%H A102762 Daniel Bach ("Dan"), <a href="http://www.dansmath.com/pages/circle.html">Kissing circles</a>.
%H A102762 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A102762 a(n) = a(1) + a(2) + a(n-1) + 2*sqrt(a(1)*a(2) + a(1)*a(n-1) + a(2)*a(n-1)) = 1 + a(n-1) + 2*(sqrt(-2 + a(n-1))). (Descartes' curvature-theorem)
%F A102762 From _Colin Barker_, Jan 07 2013: (Start)
%F A102762 a(n) = n^2 - 4*n + 6 for n > 1.
%F A102762 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 4.
%F A102762 G.f.: -(x^4 + 4*x^3 - 7*x^2 + 5*x - 1)/(x - 1)^3.
%F A102762 (End)
%o A102762 (PARI) a(n) = if(n>1, n^2 - 4*n + 6, [-1,2][n+1]) \\ _Andrew Howroyd_, Feb 25 2018
%Y A102762 Cf. A059100, A060790.
%K A102762 sign,easy
%O A102762 0,2
%A A102762 _Bodo Zinser_, Feb 10 2005