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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences:  A258546 A258547 A258548 * A258550 A258551 A258552

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 03 2015

STATUS

approved

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Last modified September 21 21:32 EDT 2021. Contains 347605 sequences. (Running on oeis4.)