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A253226 Number of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock diagonal minimum minus antidiagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal maximum nondecreasing vertically. 1
125, 306, 494, 914, 1709, 3241, 6231, 12122, 23800, 47037, 93377, 185908, 370806, 740423, 1479463, 2957334, 5912852, 11823649, 23644989, 47287400, 94571938, 189140715, 378277955, 756552106, 1513100064, 3026195621, 6052386361 (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) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4) for n>8.

Conjectures from Colin Barker, Dec 10 2018: (Start)

G.f.: x*(125 - 319*x + 89*x^2 + 323*x^3 - 307*x^4 + 76*x^5 - 3*x^6 + x^7) / ((1 - x)^3*(1 - 2*x)).

a(n) = 46 + 1443*2^(n-5) + (13*n)/2 + (15*n^2)/2 for n>4.

(End)

EXAMPLE

Some solutions for n=4:

..0..0..0..0....1..0..0..1....1..1..1..1....0..1..0..1....0..0..0..0

..1..1..0..0....1..0..0..0....0..0..0..0....0..1..0..0....0..0..0..0

..1..1..0..0....1..0..0..0....1..1..1..1....1..1..0..0....1..1..1..1

..1..1..0..0....1..0..0..0....0..0..0..0....1..1..0..0....1..0..0..0

..0..0..0..1....1..0..0..1....0..1..1..1....1..0..0..0....1..0..0..1

CROSSREFS

Column 3 of A253231.

Sequence in context: A023079 A172460 A338469 * A223182 A256362 A175486

Adjacent sequences:  A253223 A253224 A253225 * A253227 A253228 A253229

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 29 2014

STATUS

approved

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Last modified August 10 09:49 EDT 2022. Contains 356039 sequences. (Running on oeis4.)