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A159944
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Number of different deltoids (including squares) whose vertices are on an n X n grid.
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1
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0, 1, 4, 11, 26, 46, 84, 123, 194, 268, 378, 478, 657, 800, 1019, 1239, 1548, 1793, 2197, 2505, 3003, 3434, 3991, 4444, 5223, 5801, 6582, 7292, 8274, 9006, 10199, 11034, 12330, 13398, 14744, 15912, 17705, 18906, 20586
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Only convex kites (A189417) are counted, not concave kites (A173502), distinct up to congruence.
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LINKS
| Nathaniel Johnston, C program for computing terms
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EXAMPLE
| a(1) = 0, since there is only one point on a 1x1 grid.
a(2) = 1, since the four points on a 2x2 grid build a 1x1 square.
a(3) = 4 since there are 3 squares on a 3x3 grid - 1x1, 2x2, Sqrt(2)xSqrt(2), and a single non-square deltoid.
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CROSSREFS
| Cf. A189417, A173502.
Sequence in context: A079467 A140897 A008263 * A002763 A077270 A076048
Adjacent sequences: A159941 A159942 A159943 * A159945 A159946 A159947
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KEYWORD
| nonn
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AUTHOR
| Demacek Ondrej (demacek(AT)gjh.sk), Apr 27 2009
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EXTENSIONS
| Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), May 01 2011
Corrected and extended by Nathaniel Johnston (nathaniel(AT)nathanieljohnston.com) with help from Ray Chandler, May 11 2011
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