The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A190318 Number of obtuse isosceles triangles on an n X n grid. 4
 0, 0, 0, 4, 36, 100, 256, 496, 968, 1672, 2736, 4092, 6188, 8764, 12144, 16464, 22224, 28928, 37400, 47076, 59244, 73580, 90344, 109000, 132048, 158000, 187528, 220716, 259348, 301388, 350088, 402792, 463176, 529720, 602888, 683092, 774476, 872100, 978232 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS 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 LINKS Lars Blomberg, Table of n, a(n) for n = 1..10000 (the first 100 terms from Chai Wah Wu) Nathaniel Johnston, C program for computing terms FORMULA a(n) = A186434(n) - A190317(n) - A187452(n). CROSSREFS Cf. A186434, A187452, A190317, A280639. Sequence in context: A152760 A361719 A016826 * A193874 A254939 A038688 Adjacent sequences: A190315 A190316 A190317 * A190319 A190320 A190321 KEYWORD nonn AUTHOR Martin Renner, May 08 2011 EXTENSIONS a(10)-a(39) from Nathaniel Johnston, May 09 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 22 09:32 EDT 2024. Contains 372745 sequences. (Running on oeis4.)