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 A253436 Number of (2+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally. 1

%I

%S 39,58,70,102,174,318,606,1182,2334,4638,9246,18462,36894,73758,

%T 147486,294942,589854,1179678,2359326,4718622,9437214,18874398,

%U 37748766,75497502,150994974,301989918,603979806,1207959582,2415919134,4831838238

%N Number of (2+1) X (n+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.

%H R. H. Hardin, <a href="/A253436/b253436.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) - 2*a(n-2) for n>5.

%F Empirical: a(n) = 9*2^(n-1) + 30 for n>3.

%F Empirical g.f.: x*(39 - 59*x - 26*x^2 + 8*x^3 + 8*x^4) / ((1 - x)*(1 - 2*x)). - _Colin Barker_, Dec 12 2018

%e Some solutions for n=4:

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

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

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

%Y Row 2 of A253435.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 31 2014

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Last modified December 5 12:24 EST 2021. Contains 349557 sequences. (Running on oeis4.)