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%I #9 Nov 28 2017 02:11:24
%S 1,2,9,47
%N a(n) is the number of crystal forms in n dimensions.
%C a(3) is 47 or 48 depending on the classification used (whether dome and sphenoid are distinguished). Engel and the International Tables give 47. - _Andrey Zabolotskiy_, Nov 27 2017
%D P. Engel, "Geometric crystallography", in P. M. Gruber and J. M. Wills, editors, Handbook of Convex Geometry. North-Holland, Amsterdam, Vol. B, pp. 989-1041.
%D IUCr, The International Tables for Crystallography, Volume A, Table 10.1.2.3 in 2006 edition or Table 3.2.1.3 in 2016 edition.
%H Steven Dutch, <a href="https://www.uwgb.edu/dutchs/symmetry/xlforms.htm">The 48 Special Crystal Forms</a>
%H Online Dictionary of Crystallography, <a href="http://reference.iucr.org/dictionary/Form">Form</a>
%K nonn,hard
%O 0,2
%A _N. J. A. Sloane_