%I #10 Dec 05 2014 02:18:22
%S 0,0,0,1,9,39,197,721,2717,8211,19836,74497,132611,403534,1127416,
%T 2364402,4173316,15604400,21318428,73965916,154211880
%N Number of polyhexes 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/">Polyhex tiling</a>
%Y Cf. A070766, A075207, A075208, A075209, A075211, A075212, A075213, A075214, A075215, A075201, A075219.
%K hard,nonn
%O 1,5
%A _Joseph Myers_, Sep 08 2002
%E More terms from _Joseph Myers_, Nov 08 2003
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007