%I #11 Jul 05 2019 03:10:57

%S 3,6,12,12,18,21,27,27,30,36,42,42,48,48,54,54,63,69,69,69,75,78,84,

%T 84,90,96,102,102,102,102,114,114,120,123,129,129,135,141,141,141,144,

%U 150,156,156,168,168,174,174,174

%N Sizes of successive clusters in hexagonal lattice A_2 centered at deep hole.

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

%H G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/A2.html">Home page for hexagonal (or triangular) lattice A2</a>

%t CoefficientList[3 QPochhammer[q^3]^3 / QPochhammer[q] + O[q]^50, q] // Accumulate (* _Jean-François Alcover_, Jul 05 2019 *)

%Y Partial sums of A005882.

%Y Cf. A038588.

%K nonn

%O 0,1

%A _N. J. A. Sloane_.