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%I #7 Dec 18 2015 18:17:32
%S 1,60,50580,598507920,99407416968000,231753101877188629380,
%T 7583858300260627032845531520,3483475434832751291309593655505225600,
%U 22459143127863154464679826472043109609252549520
%N 1/4 the number of n X n 0..3 arrays with no element equal both to the element above and to the element to its left
%C Diagonal of A185567
%H R. H. Hardin, <a href="/A185560/b185560.txt">Table of n, a(n) for n = 1..10</a>
%e Some solutions for 3X3 with a(1,1)=0
%e ..0..1..2....0..3..2....0..0..0....0..3..2....0..2..1....0..0..0....0..0..3
%e ..3..1..1....1..2..0....1..2..2....0..0..0....1..3..0....0..2..0....3..3..0
%e ..3..3..1....1..2..0....3..3..3....1..1..3....0..1..3....0..0..2....0..0..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 31 2011