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 A250801 Number of (4+1) X (n+1) 0..1 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction. 1

%I

%S 140,490,1430,3776,9258,21610,48600,106426,228342,482496,1007546,

%T 2084962,4284032,8754018,17810278,36111264,73018218,147325946,

%U 296740456,596862762,1199199990,2407260800,4828861690,9680929586,19399411088

%N Number of (4+1) X (n+1) 0..1 arrays with nondecreasing min(x(i,j),x(i,j-1)) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.

%H R. H. Hardin, <a href="/A250801/b250801.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 9*a(n-3) + 9*a(n-4) + 6*a(n-5) - 8*a(n-6) -a(n-7) + 2*a(n-8).

%F Empirical g.f.: 2*x*(70 - 35*x - 125*x^2 + 148*x^3 + 82*x^4 - 125*x^5 - 15*x^6 + 32*x^7) / ((1 - x)^3*(1 + x)^2*(1 - 2*x)*(1 - x - x^2)). - _Colin Barker_, Nov 20 2018

%e Some solutions for n=4:

%e ..1..0..0..1..0....0..0..0..0..1....0..1..0..0..1....1..0..1..0..1

%e ..1..0..0..0..1....0..0..0..0..1....0..1..0..1..0....0..1..0..1..0

%e ..1..0..0..1..0....0..0..0..0..1....0..1..0..1..0....1..0..1..0..1

%e ..1..0..0..1..0....0..0..0..1..0....0..0..1..0..1....1..0..1..0..1

%e ..1..0..0..1..1....0..0..0..1..1....0..0..0..1..0....1..0..0..1..0

%Y Row 4 of A250797.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 27 2014

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Last modified January 22 02:46 EST 2022. Contains 350481 sequences. (Running on oeis4.)