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%I #13 May 09 2018 16:44:12
%S 0,1,1,2,2,4,2,4,4,6,4,8,4,8,8,8,6,12,6,12,10,12,8,16,10,14,12,16,10,
%T 24,10,16,16,18,16,24,12,20,18,24,14,32,14,24,24,24,16,32,18,30,24,28,
%U 18,36,24,32,26,30,20,48,20,32,32,32,28,48,22,36,32,48
%N Number of primitive inequivalent (up to Pi/3 rotation) non-hexagonal sublattices of hexagonal (triangular) lattice of index n.
%H John S. Rutherford, <a href="http://dx.doi.org/10.1107/S010876730804333X">Sublattice enumeration. IV. Equivalence classes of plane sublattices by parent Patterson symmetry and colour lattice group type</a>, Acta Cryst. (2009). A65, 156-163. [See Table 4.]
%F a(n) = (A001615(n) - A000086(n))/3. - _Andrey Zabolotskiy_, May 09 2018
%Y Cf. A000086 (primitive hexagonal sublattices), A002324 (all hexagonal sublattices), A145394 (all sublattices), A001615, A304182.
%K nonn
%O 1,4
%A _N. J. A. Sloane_, Feb 25 2009
%E New name and more terms from _Andrey Zabolotskiy_, May 09 2018
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