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 A235956 Number of (n+1) X (2+1) 0..1 arrays with the difference of the upper and lower median value of each 2 X 2 subblock in lexicographically nondecreasing order columnwise and nonincreasing rowwise. 1

%I

%S 50,228,928,3574,13346,48848,176420,631130,2242678,7930164,27941848,

%T 98196574,344438730,1206482520,4221685708,14761290914,51584989022,

%U 180196526268,629274809856,2197047322662,7669531252530,26769919917152

%N Number of (n+1) X (2+1) 0..1 arrays with the difference of the upper and lower median value of each 2 X 2 subblock in lexicographically nondecreasing order columnwise and nonincreasing rowwise.

%H R. H. Hardin, <a href="/A235956/b235956.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) - 16*a(n-2) - 22*a(n-3) + 105*a(n-4) - 66*a(n-5) - 120*a(n-6) + 176*a(n-7) - 64*a(n-8).

%F Empirical g.f.: 2*x*(25 - 86*x - 48*x^2 + 449*x^3 - 316*x^4 - 480*x^5 + 704*x^6 - 256*x^7) / ((1 - x)^2*(1 - 2*x)*(1 - x - 4*x^2)*(1 - 3*x - 4*x^2 + 8*x^3)). - _Colin Barker_, Oct 20 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 2 of A235962.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 17 2014

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Last modified November 30 11:07 EST 2021. Contains 349419 sequences. (Running on oeis4.)