

A006226


Number of abstract ndimensional crystallographic point groups.
(Formerly M1916)


2




OFFSET

1,2


REFERENCES

P. Engel, ``Geometric crystallography,'' in P. M. Gruber and J. M. Wills, editors, Handbook of Convex Geometry. NorthHolland, Amsterdam, Vol. B, pp. 9891041.
T. Janssen, Crystallographic Groups. NorthHolland, Amsterdam, 1973, p. 73.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..7.
A. C. Hurley, Finite rotation groups and crystal classes in four dimensions, Proc. Cambridge Philos. Soc. 47, (1951). 650661.
A. C. Hurley, Crystal Classes of FourDimensional Space R4, Acta Crystallog., 22 (1967), see especially p. 605.
W. Plesken and T. Schulz, Counting crystallographic groups in low dimensions, Experimental Mathematics, 9 (No. 3, 2000), 407411.
W. Plesken and T. Schulz, CARAT Homepage
Experimental Mathematics, Home Page


CROSSREFS

Cf. A004027, A004028, A004029.
Sequence in context: A037421 A083423 A068978 * A109298 A075537 A180852
Adjacent sequences: A006223 A006224 A006225 * A006227 A006228 A006229


KEYWORD

hard,nonn,more,nice


AUTHOR

N. J. A. Sloane.


EXTENSIONS

Two more terms from W. Plesken and T. Schulz (tilman(AT)momo.math.rwthaachen.de), Feb 27 2001


STATUS

approved



