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A038588
Sizes of clusters in hexagonal lattice A_2 centered at deep hole.
4
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
0,1
COMMENTS
The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
FORMULA
unique(A038587).
MATHEMATICA
CoefficientList[3 QPochhammer[q^3]^3 / QPochhammer[q] + O[q]^100, q] //
Accumulate // DeleteDuplicates (* Jean-François Alcover, Jul 05 2019 *)
CROSSREFS
Sequence in context: A345100 A162845 A239708 * A111041 A079830 A160744
KEYWORD
nonn
AUTHOR
STATUS
approved