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 A180603 Number of "pieces" of the n-th Brillouin zone of a 2D square lattice. 2
 1, 4, 8, 12, 20, 20, 12, 12, 20, 28, 44, 48, 48 (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 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

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Last modified June 16 12:38 EDT 2019. Contains 324152 sequences. (Running on oeis4.)