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A235566 Number of (n+1) X (1+1) 0..1 arrays with the difference of the upper and lower median value of each 2 X 2 subblock in lexicographically nondecreasing order rowwise and columnwise. 2
16, 50, 144, 398, 1076, 2866, 7560, 19798, 51580, 133850, 346320, 894014, 2303876, 5929090, 15242904, 39155878, 100520716, 257930666, 661586400, 1696454798, 4349091860, 11147493970, 28569027240, 73209334774, 187586107036 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A235573.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - a(n-2) - 10*a(n-3) + 8*a(n-4).

Empirical g.f.: 2*x*(8 - 7*x - 20*x^2 + 16*x^3) / ((1 - x)*(1 - 2*x)*(1 - x - 4*x^2)). - Colin Barker, Mar 19 2018

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Cf. A235573.

Sequence in context: A235962 A235573 A186850 * A186842 A231840 A199809

Adjacent sequences:  A235563 A235564 A235565 * A235567 A235568 A235569

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2014

STATUS

approved

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Last modified July 2 03:47 EDT 2022. Contains 354985 sequences. (Running on oeis4.)