%I A006227 M2104
%S A006227 1,2,17,230,4895
%N A006227 Number of n-dimensional space groups (including enantiomorphs).
%D A006227 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006227 H. Brown, R. B\"{u}low, J. Neub\"{u}ser, H. Wondratschek and H. Zassenhaus, 
               Crystallographic Groups of Four-Dimensional Space. Wiley, NY, 1978, 
               p. 52.
%D A006227 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 A006227 J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational 
               Geometry, CRC Press, 1997, p. 102.
%D A006227 T. Janssen, Crystallographic Groups. North-Holland, Amsterdam, 1973, 
               p. 119.
%D A006227 W. Plesken and T. Schulz, Counting crystallographic groups in low dimensions, 
               Experimental Mathematics, 9 (No. 3, 2000), 407-411.
%H A006227 W. Plesken and T. Schulz, <a href="http://wwwb.math.rwth-aachen.de/carat/
               ">CARAT Homepage</a>
%H A006227 Dror Bar-Natan, <a href="http://www.math.toronto.edu/~drorbn/Gallery/
               Symmetry/Tilings/index.html">Illustrations of 2-dimensional symmetry 
               groups</a>
%H A006227 Experimental Mathematics, <a href="http://www.expmath.org/">Home Page</
               a>
%Y A006227 Cf. A004029.
%Y A006227 Sequence in context: A004029 A144208 A058239 this_sequence A036082 A099694 
               A099698
%Y A006227 Adjacent sequences: A006224 A006225 A006226 this_sequence A006228 A006229 
               A006230
%K A006227 nonn,hard,nice
%O A006227 0,2
%A A006227 N. J. A. Sloane (njas(AT)research.att.com).