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%I #9 May 10 2016 09:12:31
%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,2,0,0,4,4,4,4,4,0,0,8,8,14,14,
%T 8,8,0,0,12,18,24,36,24,18,12,0,0,18,28,44,58,58,44,28,18,0,0,24,44,
%U 64,94,100,94,64,44,24,0,0,32,60,96,130,160,160,130,96
%N Array read by antidiagonals: T(n,k) = number of ways to choose 3 distinct points from an n X k rectangular grid so that they form an obtuse isosceles triangle of nonzero area.
%C A271910(n) = a(n) + A272625(n) + A272626(n).
%H Chai Wah Wu, <a href="/A272624/b272624.txt">Table of n, a(n) for n = 1..3003</a>
%H Chai Wah Wu, <a href="http://arxiv.org/abs/1605.00180">Counting the number of isosceles triangles in rectangular regular grids</a>, arXiv:1605.00180 [math.CO], 2016.
%F T(n,k) = 2*T(n,k-1)-2*T(n,k-3)+T(n,k-4) for k > max(7,(n-1)^2+2) if n is odd and for k > (n-1)^2+3) if n is even.
%Y Cf. A271910, A272625, A272626.
%K nonn,tabl
%O 1,17
%A _Chai Wah Wu_, May 07 2016
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