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Number of contraction types of n-dimensional parallelohedra.
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%I #16 Mar 02 2019 12:07:16

%S 1,1,2,5,52,179372

%N Number of contraction types of n-dimensional parallelohedra.

%C Or, number of inequivalent Delaunay [Delone] decompositions of R^n.

%C Sikiric et al. say that actually a(5) = 181394. - _Andrey Zabolotskiy_, Mar 02 2019

%H Mathieu Dutour Sikirić, Alexey Garber, Achill Schürmann, Clara Waldmann, <a href="https://doi.org/10.1107/S2053273316011682">The complete classification of five-dimensional Dirichlet-Voronoi polyhedra of translational lattices</a>, Acta Crystallographica A72 (2016), 673-683; arXiv:<a href="https://arxiv.org/abs/1507.00238">1507.00238</a> [math.MG], 2015-2016.

%H P. Engel, <a href="https://doi.org/10.1107/S0108767300007145">The contraction types of parallelohedra in E^5</a>, Acta Cryst. A 56 (2000), 491-496.

%H M. I. Stogrin, <a href="http://mi.mathnet.ru/eng/tm3121">Regular Dirichlet-Voronoi partitions for the second triclinic group</a>, Trudy Matematicheskogo Instituta imeni V. A. Steklova, 123 (1973) = Proceedings of the Steklov Institute of Mathematics, 123 (1973).

%Y Cf. A071880, A071881.

%K nonn,hard,nice,more

%O 0,3

%A _N. J. A. Sloane_, Jun 10 2002