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A235291 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 3 (constant stress 1 X 1 tilings). 1
40, 108, 272, 744, 1888, 5232, 13376, 37536, 96640, 274368, 710912, 2039424, 5314048, 15382272, 40272896, 117459456, 308746240, 906083328, 2389348352, 7047112704, 18631057408, 55167578112, 146146082816, 434084683776 (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) = 14*a(n-2) - 48*a(n-4).

Empirical g.f.: 4*x*(10 + 27*x - 72*x^2 - 192*x^3) / ((1 - 6*x^2)*(1 - 8*x^2)). - Colin Barker, Oct 18 2018

EXAMPLE

Some solutions for n=5:

..3..0....2..2....3..0....1..3....1..1....3..0....0..1....3..3....1..0....1..3

..1..1....3..0....1..1....2..1....0..3....2..2....3..1....0..3....0..2....3..2

..3..0....1..1....3..0....0..2....1..1....3..0....0..1....1..1....1..0....0..2

..0..0....3..0....2..2....2..1....0..3....2..2....3..1....3..0....0..2....1..0

..0..3....1..1....3..0....1..3....3..3....3..0....0..1....3..3....1..0....1..3

..1..1....3..0....1..1....1..0....3..0....2..2....3..1....0..3....1..3....1..0

CROSSREFS

Column 1 of A235301.

Sequence in context: A241024 A123992 A235301 * A235893 A192791 A345970

Adjacent sequences:  A235288 A235289 A235290 * A235292 A235293 A235294

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2014

STATUS

approved

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Last modified January 17 17:47 EST 2022. Contains 350402 sequences. (Running on oeis4.)