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%I #4 Jan 16 2014 13:34:09
%S 21,105,453,1833,7221,28185,109893,429513,1684821,6633465,26204133,
%T 103802793,412120821,1639113945
%N Number of (n+1)X(n+1) 0..2 arrays with the minimum plus the upper median equal to the lower median plus the maximum in every 2X2 subblock
%C Diagonal of A235884
%F Empirical: a(n) = 10*a(n-1) -35*a(n-2) +50*a(n-3) -24*a(n-4)
%e Some solutions for n=5
%e ..2..1..1..2..2..2....0..0..0..0..0..1....2..2..2..2..0..2....1..0..0..0..1..1
%e ..1..2..2..1..1..1....0..0..0..0..0..1....2..2..2..2..0..2....0..1..1..1..0..0
%e ..2..1..1..2..2..2....0..0..0..0..0..1....0..0..0..0..2..0....0..1..1..1..0..0
%e ..2..1..1..2..2..2....0..0..0..0..0..1....2..2..2..2..0..2....0..1..1..1..0..0
%e ..1..2..2..1..1..1....0..0..0..0..0..1....2..2..2..2..0..2....0..1..1..1..0..0
%e ..2..1..1..2..2..2....0..0..0..0..0..1....0..0..0..0..2..0....0..1..1..1..0..0
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 16 2014