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%I #11 Dec 05 2014 02:42:35
%S 0,0,0,0,1,22,38,504,1468,6945,11046,115186,119496,677774,2013619
%N Number of polyiamonds with 2n cells that tile the plane by translation but not by 180-degree rotation (Conway criterion).
%C Polyiamonds with an odd number of cells have different numbers of triangles with the two orientations and so cannot tile by translation.
%D Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.
%H Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyiamond tiling</a>
%Y Cf. A071332, A075216, A075218, A075219, A075220, A075221, A075222, A075223, A075224, A075199, A075208.
%K hard,nonn
%O 1,6
%A _Joseph Myers_, Sep 08 2002
%E More terms from _Joseph Myers_, Nov 11 2003
%E a(15) (30-iamonds) from _Joseph Myers_, Nov 21 2010
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