A038588 Sizes of clusters in hexagonal lattice A_2 centered at deep hole.

3, 6, 12, 18, 21, 27, 30, 36, 42, 48, 54, 63, 69, 75, 78, 84, 90, 96, 102, 114, 120, 123, 129, 135, 141, 144, 150, 156, 168, 174, 180, 186, 192, 198, 207, 213, 219, 225, 231, 240, 246, 252, 258, 270, 276, 282

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.

Links

• G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2

Crossrefs

Cf. A005882, A038587.

Programs

Mathematica

CoefficientList[3 QPochhammer[q^3]^3 / QPochhammer[q] + O[q]^100, q] //
Accumulate // DeleteDuplicates (* Jean-François Alcover, Jul 05 2019 *)

Formula

unique(A038587).