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A180604 Number of "pieces" of the n-th Brillouin zone of a 2D hexagonal lattice. 0
1, 6, 6, 6, 12, 18, 30, 30, 18, 18, 36, 42, 54, 54, 42, 66 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Each Brillouin zone has the same area, and they are all equivalent mod the periodicity of the lattice, but the higher-order ones consist of a set of polygons. This is the number of polygons in that set.

LINKS

Table of n, a(n) for n=1..16.

EXAMPLE

The 2nd Brillouin zone consists of 6 equilateral triangles, so a(2) = 6. The 5th Brillouin zone consists of 12 30-60-90 triangles, so a(5) = 12.

CROSSREFS

Sequence in context: A315827 A315828 A315829 * A254572 A109047 A337814

Adjacent sequences:  A180601 A180602 A180603 * A180605 A180606 A180607

KEYWORD

nonn,more

AUTHOR

Keenan Pepper, Sep 11 2010

STATUS

approved

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Last modified June 21 16:27 EDT 2021. Contains 345365 sequences. (Running on oeis4.)