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A241229
Number of acute isosceles triangles on a centered hexagonal grid of size n.
2
0, 8, 144, 768, 2558, 6564, 14334, 27626, 48828, 80772, 126692, 190230, 275700, 388016, 532386, 714906, 941600, 1219410, 1556184, 1959608, 2438868, 3002700
OFFSET
1,2
COMMENTS
A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.
LINKS
Eric Weisstein's World of Mathematics, Hex Number.
Eric Weisstein's World of Mathematics, Acute Triangle.
Eric Weisstein's World of Mathematics, Isosceles Triangle.
FORMULA
a(n) = A241228(n) - A241230(n).
CROSSREFS
Cf. A190317.
Sequence in context: A275034 A275139 A370071 * A274730 A263604 A212703
KEYWORD
nonn,more
AUTHOR
Martin Renner, Apr 17 2014
EXTENSIONS
a(7) from Martin Renner, May 31 2014
a(8)-a(22) from Giovanni Resta, May 31 2014
STATUS
approved