%I
%S 5,10,18,36,66,132,244,488,906,1812,3372,6744,12566,25132,46860,93720,
%T 174810,349620,652252,1304504,2433942,4867884,9083004,18166008,
%U 33897050,67794100,126503148,253006296,472111446,944222892,1761934444,3523868888
%N Number of zigzag paths from top to bottom of a rectangle of width 11 with n rows whose color is not that of the top right corner.
%H Joseph Myers, <a href="http://www.polyomino.org.uk/publications/2008/bmo12009q1.pdf">BMO 20082009 Round 1 Problem 1Generalisation</a>
%F Empirical: G.f. x*(2*x+1)*(3*x^412*x^2+5) / ( (2*x^21)*(x^44*x^2+1) ) and a(n)= +6*a(n2) 9*a(n4) +2*a(n6).  _R. J. Mathar_, Jun 16 2011
%Y A153368, A153369, A153372. Bisections: A153371, A153373.
%K easy,nonn
%O 1,1
%A _Joseph Myers_, Dec 24 2008
