A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.
Table of n, a(n) for n=1..13.
Eric Weisstein's World of Mathematics, Hex Number.
Eric Weisstein's World of Mathematics, Scalene Triangle.
a(n) = A241231(n) - A241237(n).
For n = 2 the only kind of non-congruent scalene triangles is the following:
* . *
Cf. A190313, A241227.
Sequence in context: A086120 A129701 A221746 * A044270 A044651 A287303
Adjacent sequences: A241233 A241234 A241235 * A241237 A241238 A241239
Martin Renner, Apr 17 2014
a(7) from Martin Renner, May 31 2014
a(8)-a(13) from Giovanni Resta, May 31 2014