%I #11 Dec 05 2014 02:42:19
%S 1,1,3,7,22,76,290,1018,3715,11068,24289,102642,163176,527675,1569567,
%T 2929322,4752512,21006062,24293375,95578494,205091895
%N Number of polyhexes with n cells that tile the plane isohedrally.
%C A tiling is isohedral if the symmetries of the tiling act transitively on the tiles; a shape is anisohedral if it tiles the plane, but not isohedrally.
%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/">Polyhex tiling</a>
%Y Cf. A070766, A075207, A075208, A075209, A075210, A075211, A075212, A075213, A075215, A075205, A075223.
%K hard,nonn
%O 1,3
%A _Joseph Myers_, Sep 08 2002
%E More terms from _Joseph Myers_, Nov 08 2003
%E a(20) and a(21) from _Joseph Myers_, Nov 21 2010