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A235673 Number of (n+1) X (2+1) 0..1 arrays with the difference between each 2 X 2 subblock maximum and minimum lexicographically nondecreasing columnwise and nonincreasing rowwise. 1
58, 380, 2456, 15790, 101398, 650928, 4178316, 26820102, 172154058, 1105028596, 7092994476, 45528746034, 292241404878, 1875848682364, 12040758823136, 77287616186486, 496096276240318, 3184358988382152, 20439867526684676 (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) = 8*a(n-1) - 9*a(n-2) - 9*a(n-3) + 10*a(n-4) + 3*a(n-5) - 2*a(n-6).

Empirical g.f.: 2*x*(29 - 42*x - 31*x^2 + 42*x^3 + 11*x^4 - 8*x^5) / ((1 - x)*(1 - x - x^2)*(1 - 6*x - 3*x^2 + 2*x^3)). - Colin Barker, Oct 19 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Column 2 of A235679.

Sequence in context: A141779 A250927 A250920 * A235730 A235443 A235511

Adjacent sequences:  A235670 A235671 A235672 * A235674 A235675 A235676

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 13 2014

STATUS

approved

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Last modified August 3 12:51 EDT 2021. Contains 346438 sequences. (Running on oeis4.)