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A250538 Number of (n+1)X(2+1) 0..3 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction.

%I A250538 #6 Jul 23 2025 12:31:17
%S A250538 1080,10704,79366,491650,2701872,13657024,64993652,295871112,
%T A250538 1302924116,5595784456,23580939154,97951328382,402468021792,
%U A250538 1640200686104,6643744925312,26790344223060,107678819237476,431796331093984
%N A250538 Number of (n+1)X(2+1) 0..3 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction.
%C A250538 Column 2 of A250544
%H A250538 R. H. Hardin, <a href="/A250538/b250538.txt">Table of n, a(n) for n = 1..210</a>
%F A250538 Empirical: a(n) = 30*a(n-1) -415*a(n-2) +3514*a(n-3) -20386*a(n-4) +85924*a(n-5) -272198*a(n-6) +661180*a(n-7) -1244717*a(n-8) +1822478*a(n-9) -2068955*a(n-10) +1802474*a(n-11) -1181760*a(n-12) +563888*a(n-13) -184752*a(n-14) +37152*a(n-15) -3456*a(n-16)
%e A250538 Some solutions for n=3
%e A250538 ..3..2..1....2..0..2....2..0..0....2..0..1....3..2..2....3..1..0....3..3..0
%e A250538 ..2..1..0....2..1..3....2..1..1....2..2..3....2..1..1....1..1..1....2..2..0
%e A250538 ..2..2..2....1..0..2....1..2..3....0..0..1....1..0..0....1..1..3....2..3..1
%e A250538 ..0..3..3....0..1..3....1..2..3....2..2..3....1..1..3....0..0..3....1..3..3
%K A250538 nonn
%O A250538 1,1
%A A250538 _R. H. Hardin_, Nov 24 2014