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A190309
Number of acute isosceles triangles, distinct up to congruence, on an n X n grid (or geoboard).
2
0, 0, 2, 5, 11, 19, 29, 40, 58, 74, 94, 113, 141, 168, 201, 227, 267, 304, 348, 390, 438, 483, 537, 590, 657, 709, 776, 837, 913, 979, 1057, 1130, 1225, 1299, 1396, 1472, 1576, 1663, 1768, 1863, 1974
OFFSET
1,3
LINKS
Eric Weisstein's World of Mathematics, Geoboard.
Eric Weisstein's World of Mathematics, Acute Triangle.
Eric Weisstein's World of Mathematics, Isosceles Triangle.
FORMULA
a(n) = A189978(n) - A190310(n) - A108279(n).
CROSSREFS
KEYWORD
nonn
AUTHOR
Martin Renner, May 08 2011
STATUS
approved