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A253152 Number of (n+1) X (1+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally and vertically. 2
16, 39, 69, 109, 181, 325, 613, 1189, 2341, 4645, 9253, 18469, 36901, 73765, 147493, 294949, 589861, 1179685, 2359333, 4718629, 9437221, 18874405, 37748773, 75497509, 150994981, 301989925, 603979813, 1207959589, 2415919141, 4831838245 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A253159.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) -2*a(n-2) for n>5.

Empirical: a(n) = 9*2^(n-1) + 37 for n>3.

Empirical g.f.: x*(16 - 9*x - 16*x^2 - 20*x^3 - 8*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Mar 20 2018

EXAMPLE

Some solutions for n=6:

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

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

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

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

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

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

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

CROSSREFS

Cf. A253159.

Sequence in context: A121375 A342976 A347410 * A305362 A197603 A144448

Adjacent sequences:  A253149 A253150 A253151 * A253153 A253154 A253155

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 28 2014

STATUS

approved

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Last modified January 27 13:38 EST 2022. Contains 350607 sequences. (Running on oeis4.)