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A253155
Number of (n+1) X (4+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally and vertically.
1
109, 120, 129, 164, 236, 380, 668, 1244, 2396, 4700, 9308, 18524, 36956, 73820, 147548, 295004, 589916, 1179740, 2359388, 4718684, 9437276, 18874460, 37748828, 75497564, 150995036, 301989980, 603979868, 1207959644, 2415919196, 4831838300
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) for n>5.
Empirical: a(n) = 9*2^(n-1) + 92 for n>3.
Empirical g.f.: x*(109 - 207*x - 13*x^2 + 17*x^3 + 2*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Dec 09 2018
EXAMPLE
Some solutions for n=6:
..0..1..1..1..1....0..0..0..0..0....1..0..0..0..1....0..0..0..1..0
..0..0..0..0..0....1..1..1..1..1....1..0..0..0..1....1..0..0..1..0
..1..1..1..1..1....1..1..1..1..1....1..0..0..0..1....1..0..0..1..0
..1..1..1..1..1....1..1..1..1..1....1..0..0..0..1....1..0..0..1..0
..0..0..0..0..0....0..0..0..0..0....1..0..0..0..1....1..0..0..1..0
..0..0..0..0..0....1..1..1..1..1....1..0..0..0..1....1..0..0..1..0
..0..0..0..0..1....0..0..0..0..0....1..0..0..0..1....1..0..0..1..1
CROSSREFS
Column 4 of A253159.
Sequence in context: A196673 A159027 A039492 * A095609 A046295 A164288
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 28 2014
STATUS
approved