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%I #7 Aug 16 2013 05:16:57
%S 1,6,6,6,12,18,30,30,18,18,36,42,54,54,42,66
%N Number of "pieces" of the n-th Brillouin zone of a 2D hexagonal lattice.
%C 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.
%e 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.
%K nonn,more
%O 1,2
%A _Keenan Pepper_, Sep 11 2010
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