%I #6 Dec 28 2017 06:42:39
%S 0,0,2,4,10,20,44,92,194,396,820,1684,3432,6972,14144,28636,57890,
%T 116828,235500,474304,954444,1919364,3857548,7748888,15558988,
%U 31229384,62662088,125696800,252079196,505423476,1013189208,2030729700,4069562810,8154257184,16336840080,32726819744,65553540096
%N Number of open binary words of length n.
%C Equals 2^n - A226452(n).
%H Gabriele Fici, <a href="http://bulletin.eatcs.org/index.php/beatcs/article/viewFile/508/497">Open and Closed Words</a>, in Giovanni Pighizzini, ed., The Formal Language Theory Column, Bulletin of EATCS, 2017.
%Y Cf. A226452.
%K nonn
%O 0,3
%A _N. J. A. Sloane_, Dec 28 2017