

A180603


Number of "pieces" of the nth Brillouin zone of a 2D square lattice.


2



1, 4, 8, 12, 20, 20, 12, 12, 20, 28, 44, 48, 48
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OFFSET

1,2


COMMENTS

Each Brillouin zone has the same area, and they are all equivalent mod the periodicity of the lattice, but the higherorder 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..13.


EXAMPLE

The 2nd Brillouin zone consists of 4 right isosceles triangles, so a(2) = 4. The 4th Brillouin zone consists of 8 triangles and 4 kites, so a(4) = 12.


CROSSREFS

Sequence in context: A311648 A026042 A196377 * A311649 A311650 A311651
Adjacent sequences: A180600 A180601 A180602 * A180604 A180605 A180606


KEYWORD

nonn,more


AUTHOR

Keenan Pepper, Sep 11 2010


STATUS

approved



