%I #7 Mar 09 2015 04:32:25

%S 1,2,1,11,8,269,85,16334,5933,4005785,817280,2758179839,505375405,

%T 6795928721858,826573277157,51247532773412135,4982395765808506,

%U 1302848440978689378895,90454037365096154821

%N Number of n X n binary matrices, symmetric under horizontal reflection, with no more than 1 one in any 2 X 2 subblock.

%H R. H. Hardin, Aug 09 2008, <a href="/A141482/b141482.txt">Table of n, a(n) for n = 0..30</a>

%K nonn

%O 0,2

%A _R. H. Hardin_, Aug 09 2008