%I A004031 M3317
%S A004031 1,1,4,7,33
%N A004031 Number of n-dimensional crystal systems.
%D A004031 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A004031 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 A004031 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.
%Y A004031 Sequence in context: A156228 A000289 A149089 this_sequence A153062 A143547 
               A149090
%Y A004031 Adjacent sequences: A004028 A004029 A004030 this_sequence A004032 A004033 
               A004034
%K A004031 nonn,hard,nice
%O A004031 0,3
%A A004031 N. J. A. Sloane (njas(AT)research.att.com).