%I #5 Mar 31 2012 13:21:47
%S 0,1,3,6,10,15,21,28,34,40,46,52,58,64,70,76,82,88,94,100,106,112,118,
%T 124,130,136,142,148,154,160,166,172,178,184,190,196,202,208,214,220,
%U 226,232,238,244,250,256,262,268,274,280,286,292,298,304,310,316,322,328,334,340
%N Maximal number of edges in a rectangle visibility graph with n nodes.
%C If Y is a 3-subset of an 2n-set X then, for n>=6, a(n+1) is the number of 3-subsets of X having at least two elements in common with Y. - _Milan Janjic_, Dec 16 2007
%D L. W. Beineke, Biplanar graphs: a survey, Computers Math. Applic., 34 (1997), 1-8.
%D Hutchinson, Joan P.; Shermer, Thomas; and Vince, Andrew; On representations of some thickness-two graphs. Comput. Geom. 13 (1999), 161-171.
%F If n <= 8 then n*(n-1)/2 else 6*n-20.
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Dec 02 2006