login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075217 Number of polyiamonds with 2n cells that tile the plane by translation but not by 180-degree rotation (Conway criterion). 10
0, 0, 0, 0, 1, 22, 38, 504, 1468, 6945, 11046, 115186, 119496, 677774, 2013619 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Polyiamonds with an odd number of cells have different numbers of triangles with the two orientations and so cannot tile by translation.

REFERENCES

Branko Gr├╝nbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.

LINKS

Table of n, a(n) for n=1..15.

Joseph Myers, Polyiamond tiling

CROSSREFS

Cf. A071332, A075216, A075218, A075219, A075220, A075221, A075222, A075223, A075224, A075199, A075208.

Sequence in context: A043196 A043976 A131196 * A188156 A026061 A138040

Adjacent sequences:  A075214 A075215 A075216 * A075218 A075219 A075220

KEYWORD

hard,nonn

AUTHOR

Joseph Myers, Sep 08 2002

EXTENSIONS

More terms from Joseph Myers, Nov 11 2003

a(15) (30-iamonds) from Joseph Myers, Nov 21 2010

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 26 12:33 EST 2020. Contains 332279 sequences. (Running on oeis4.)