A241225 Number of right triangles on a centered hexagonal grid of size n.

0, 12, 216, 1104, 3708, 9396, 20304, 38868, 68364, 112632, 176076, 263832, 381924, 536424, 735240, 985896, 1296540, 1676508, 2137392, 2689248, 3344244, 4114020

Offset

1,2

Comments

A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.

Links

Table of n, a(n) for n=1..22.

Eric Weisstein's World of Mathematics, Hex Number.

Eric Weisstein's World of Mathematics, Right Triangle.

Formula

a(n) = A241223(n) - A241224(n) - A241226(n).

Crossrefs

Cf. A077435.

Sequence in context: A262739 A027487 A276245 * A274956 A116164 A268369

Adjacent sequences: A241222 A241223 A241224 * A241226 A241227 A241228

Keyword

nonn

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