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A253225 Number of (n+1) X (2+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
47, 132, 306, 742, 1775, 4158, 9551, 21591, 48179, 106371, 232787, 505683, 1091603, 2343699, 5008403, 10658835, 22601747, 47771667, 100679699, 211632147, 443809811, 928710675, 1939603475, 4043571219, 8415870995, 17489199123 (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) - 8*a(n-2) + 4*a(n-3) for n>7.

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

G.f.: x*(47 - 103*x + 22*x^2 + 80*x^3 - 15*x^4 - 5*x^5 - 7*x^6) / ((1 - x)*(1 - 2*x)^2).

a(n) = 19 + 377*2^(n-6) + 627*2^(n-6)*n for n>4.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A253231.

Sequence in context: A044298 A044679 A350863 * A039530 A288408 A095311

Adjacent sequences:  A253222 A253223 A253224 * A253226 A253227 A253228

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 29 2014

STATUS

approved

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Last modified May 28 03:28 EDT 2022. Contains 354110 sequences. (Running on oeis4.)