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%I #26 May 28 2021 18:44:08
%S 0,0,0,4,36,100,256,496,968,1672,2736,4092,6188,8764,12144,16464,
%T 22224,28928,37400,47076,59244,73580,90344,109000,132048,158000,
%U 187528,220716,259348,301388,350088,402792,463176,529720,602888,683092,774476,872100,978232
%N Number of obtuse isosceles triangles on an n X n grid.
%C Place all bounding boxes of A280639 that will fit into the n X n grid in all possible positions, and the proper rectangles in two orientations: a(n) = Sum(i=1..n, Sum(j=1..i, k * (n-i+1) * (n-j+1) * A280639(i,j))) where k=1 when i=j and k=2 otherwise. - _Lars Blomberg_, Mar 02 2017
%H Lars Blomberg, <a href="/A190318/b190318.txt">Table of n, a(n) for n = 1..10000</a> (the first 100 terms from Chai Wah Wu)
%H Nathaniel Johnston, <a href="/A190318/a190318.c.txt">C program for computing terms</a>
%F a(n) = A186434(n) - A190317(n) - A187452(n).
%Y Cf. A186434, A187452, A190317, A280639.
%K nonn
%O 1,4
%A _Martin Renner_, May 08 2011
%E a(10)-a(39) from _Nathaniel Johnston_, May 09 2011
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