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A235653 Number of (n+1) X (1+1) 0..1 arrays with the difference of the upper median and minimum value of each 2 X 2 subblock in lexicographically nondecreasing order rowwise and columnwise. 2
16, 52, 160, 476, 1392, 4020, 11520, 32828, 93200, 263892, 745824, 2105116, 5936304, 16729076, 47122368, 132690428, 373551952, 1051454740, 2959233056, 8327823580, 23434631152, 65942655540, 185550334592, 522092927932, 1469018657424 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A235660.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - a(n-2) - 8*a(n-3) + 4*a(n-4).

Empirical g.f.: 4*x*(4 - 3*x - 8*x^2 + 4*x^3) / ((1 - 2*x)*(1 - 2*x - 3*x^2 + 2*x^3)). - Colin Barker, Mar 19 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Cf. A235660.

Sequence in context: A217736 A211578 A211592 * A087701 A211586 A232509

Adjacent sequences:  A235650 A235651 A235652 * A235654 A235655 A235656

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 13 2014

STATUS

approved

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Last modified April 15 19:21 EDT 2021. Contains 342977 sequences. (Running on oeis4.)