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A235956 Number of (n+1) X (2+1) 0..1 arrays with the difference of the upper and lower median value of each 2 X 2 subblock in lexicographically nondecreasing order columnwise and nonincreasing rowwise. 1
50, 228, 928, 3574, 13346, 48848, 176420, 631130, 2242678, 7930164, 27941848, 98196574, 344438730, 1206482520, 4221685708, 14761290914, 51584989022, 180196526268, 629274809856, 2197047322662, 7669531252530, 26769919917152 (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) - 16*a(n-2) - 22*a(n-3) + 105*a(n-4) - 66*a(n-5) - 120*a(n-6) + 176*a(n-7) - 64*a(n-8).

Empirical g.f.: 2*x*(25 - 86*x - 48*x^2 + 449*x^3 - 316*x^4 - 480*x^5 + 704*x^6 - 256*x^7) / ((1 - x)^2*(1 - 2*x)*(1 - x - 4*x^2)*(1 - 3*x - 4*x^2 + 8*x^3)). - Colin Barker, Oct 20 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A235962.

Sequence in context: A250527 A251065 A231087 * A197971 A235567 A091883

Adjacent sequences:  A235953 A235954 A235955 * A235957 A235958 A235959

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 17 2014

STATUS

approved

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Last modified October 15 21:38 EDT 2021. Contains 348034 sequences. (Running on oeis4.)