A006226 - OEIS

%I M1916 #40 Nov 06 2017 02:39:23

%S 1,2,9,18,118,239,1594

%N Number of abstract n-dimensional crystallographic point groups.

%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 T. Janssen, Crystallographic Groups. North-Holland, Amsterdam, 1973, p. 73.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H A. C. Hurley, <a href="http://dx.doi.org/10.1017/S0305004100027109">Finite rotation groups and crystal classes in four dimensions</a>, Proc. Cambridge Philos. Soc. 47, (1951). 650-661.

%H A. C. Hurley, <a href="http://dx.doi.org/10.1107/S0365110X67001227">Crystal Classes of Four-Dimensional Space R4</a>, Acta Crystallog., 22 (1967), see especially p. 605.

%H W. Plesken and T. Schulz, <a href="http://projecteuclid.org/euclid.em/1045604675">Counting crystallographic groups in low dimensions</a>, Experimental Mathematics, 9 (No. 3, 2000), 407-411.

%H W. Plesken and T. Schulz, <a href="http://wwwb.math.rwth-aachen.de/carat/">CARAT Homepage</a>

%H W. Plesken and T. Schulz, <a href="/A006226/a006226.pdf">CARAT Homepage</a> [Cached copy in pdf format (without subsidiary pages), with permission]

%H W. Plesken and T. Schulz, <a href="/A006226/a006226_1.pdf">Introduction to CARAT</a> [Cached copy in pdf format (without subsidiary pages), with permission]

%H E. S. Rosenthal & N. J. A. Sloane, <a href="/A004028/a004028.pdf">Correspondence, 1975</a>

%Y Cf. A004027, A004028, A004029.

%K hard,nonn,more,nice

%O 0,2

%A _N. J. A. Sloane_

%E Two more terms from W. Plesken and T. Schulz (tilman(AT)momo.math.rwth-aachen.de), Feb 27 2001

%E Offset corrected by _Andrey Zabolotskiy_, Jul 10 2017