A241229 Number of acute isosceles triangles on a centered hexagonal grid of size n.

0, 8, 144, 768, 2558, 6564, 14334, 27626, 48828, 80772, 126692, 190230, 275700, 388016, 532386, 714906, 941600, 1219410, 1556184, 1959608, 2438868, 3002700

Offset: 1

Author

Martin Renner, Apr 17 2014

Keywords

• nonn
• more

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.

Crossrefs

Cf. A190317.

Formula

a(n) = A241228(n) - A241230(n).

Extensions

a(7) from Martin Renner, May 31 2014

a(8)-a(22) from Giovanni Resta, May 31 2014