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A075219
Number of polyiamonds with n cells that tile the plane by 180-degree rotation (Conway criterion) but not by translation.
10
1, 0, 1, 1, 4, 4, 21, 32, 111, 200, 462, 1162, 1875, 4195, 9410, 17978, 24034, 73175, 79925, 251808, 358096, 631919, 796571, 3104082, 2980476, 6088310, 10167660, 23661369, 21477012, 84485584
OFFSET
1,5
REFERENCES
Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.
KEYWORD
hard,nonn
AUTHOR
Joseph Myers, Sep 08 2002
EXTENSIONS
More terms from Joseph Myers, Nov 11 2003
a(29) and a(30) from Joseph Myers, Nov 21 2010
STATUS
approved