The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A190310 Number of obtuse isosceles triangles, distinct up to congruence, on a (n X n)-grid (or geoboard). 2
 0, 0, 0, 1, 3, 5, 9, 12, 19, 24, 32, 37, 51, 57, 69, 80, 99, 107, 127, 136, 161, 176, 196, 207, 246, 262, 286, 306, 343, 357, 399, 414, 460, 485, 517, 544, 605, 623, 659, 689, 757 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS Barile, Margherita: MathWorld -- Geoboard. Weisstein, Eric W.: MathWorld -- Obtuse Triangle. Weisstein, Eric W.: MathWorld -- Isosceles Triangle. FORMULA a(n) = A189978(n) - A190309(n) - A108279(n). CROSSREFS Cf. A028419, A108279, A189978, A190022, A190309. Sequence in context: A211538 A247799 A265702 * A046746 A058599 A238662 Adjacent sequences:  A190307 A190308 A190309 * A190311 A190312 A190313 KEYWORD nonn AUTHOR Martin Renner, May 08 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 29 04:27 EDT 2020. Contains 334696 sequences. (Running on oeis4.)