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A258549
Number of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.
1
104, 210, 598, 1244, 2384, 3980, 6348, 9567, 13847, 19227, 26071, 34506, 44790, 57010, 71578, 88669, 108589, 131473, 157781, 187736, 221692, 259832, 302664, 350459, 403619, 462375, 527283, 598662, 676962, 762462, 855766, 957241, 1067385
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - 4*a(n-5) + 6*a(n-6) - 4*a(n-7) + a(n-8) for n>11.
Empirical g.f.: x*(104 - 206*x + 382*x^2 - 304*x^3 + 156*x^4 - 68*x^5 - 28*x^6 + 67*x^7 - 129*x^8 + 103*x^9 - 29*x^10) / ((1 - x)^5*(1 + x)*(1 + x^2)). - Colin Barker, Dec 21 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0....0..0..0..1....0..1..1..1....0..0..0..1....0..0..0..1
..1..1..1..1....0..0..0..1....1..1..0..0....0..0..0..0....0..0..0..0
..0..0..0..0....0..0..0..1....1..0..0..1....0..0..0..1....0..0..0..0
..1..1..1..1....1..0..0..1....1..1..1..1....1..1..1..1....0..0..0..0
..1..1..0..1....1..1..0..1....1..1..0..0....1..1..0..1....0..0..0..1
CROSSREFS
Column 3 of A258554.
Sequence in context: A235990 A270300 A108665 * A121962 A235011 A271745
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 03 2015
STATUS
approved