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Number of polyiamonds with n cells that tile the plane by 180-degree rotation (Conway criterion) but not by translation.
10

%I #11 Dec 05 2014 02:43:13

%S 1,0,1,1,4,4,21,32,111,200,462,1162,1875,4195,9410,17978,24034,73175,

%T 79925,251808,358096,631919,796571,3104082,2980476,6088310,10167660,

%U 23661369,21477012,84485584

%N Number of polyiamonds with n cells that tile the plane by 180-degree rotation (Conway criterion) but not 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, A075217, A075218, A075220, A075221, A075222, A075223, A075224, A075201, A075210.

%K hard,nonn

%O 1,5

%A _Joseph Myers_, Sep 08 2002

%E More terms from _Joseph Myers_, Nov 11 2003

%E a(29) and a(30) from _Joseph Myers_, Nov 21 2010