%I #5 Dec 18 2015 18:18:14
%S 1,15,507,65251,33407143,68410191725,560375293762217
%N Hilltop maps: number of n X n binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..3 n X n array
%C Diagonal of A218196
%e Some solutions for n=3
%e ..1..1..1....0..0..1....0..0..0....1..1..0....0..0..0....1..0..0....0..0..1
%e ..0..0..0....1..1..0....0..0..0....1..1..1....0..0..0....1..0..0....1..0..1
%e ..1..0..1....0..0..1....1..1..0....1..0..0....0..1..0....1..1..0....1..1..1
%K nonn
%O 1,2
%A _R. H. Hardin_ Oct 23 2012
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