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 A190318 #26 May 28 2021 18:44:08 %S A190318 0,0,0,4,36,100,256,496,968,1672,2736,4092,6188,8764,12144,16464, %T A190318 22224,28928,37400,47076,59244,73580,90344,109000,132048,158000, %U A190318 187528,220716,259348,301388,350088,402792,463176,529720,602888,683092,774476,872100,978232 %N A190318 Number of obtuse isosceles triangles on an n X n grid. %C A190318 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 A190318 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 A190318 Nathaniel Johnston, <a href="/A190318/a190318.c.txt">C program for computing terms</a> %F A190318 a(n) = A186434(n) - A190317(n) - A187452(n). %Y A190318 Cf. A186434, A187452, A190317, A280639. %K A190318 nonn %O A190318 1,4 %A A190318 _Martin Renner_, May 08 2011 %E A190318 a(10)-a(39) from _Nathaniel Johnston_, May 09 2011