OFFSET
0,3
REFERENCES
H. Brown, R. Bülow, J. Neubüser, H. Wondratschek and H. Zassenhaus, Crystallographic Groups of Four-Dimensional Space. Wiley, NY, 1978, p. 52.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
W. Plesken and T. Schulz, Counting crystallographic groups in low dimensions, Experimental Mathematics, Volume 9 Issue 3 (2000), 321-478
Wikipedia, Space_group
CROSSREFS
KEYWORD
hard,nonn,nice
AUTHOR
EXTENSIONS
a(5)-a(6) from Henry Bottomley, Feb 03 2014
STATUS
approved