login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A006226 Number of abstract n-dimensional crystallographic point groups.
(Formerly M1916)
10
1, 2, 9, 18, 118, 239, 1594 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

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.

T. Janssen, Crystallographic Groups. North-Holland, 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). 650-661.

A. C. Hurley, Crystal Classes of Four-Dimensional 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), 407-411.

W. Plesken and T. Schulz, CARAT Homepage

W. Plesken and T. Schulz, CARAT Homepage [Cached copy in pdf format (without subsidiary pages), with permission]

W. Plesken and T. Schulz, Introduction to CARAT [Cached copy in pdf format (without subsidiary pages), with permission]

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.rwth-aachen.de), Feb 27 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 4 23:10 EST 2016. Contains 278755 sequences.