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A184223 Half the number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock diagonal sum differing from its antidiagonal sum by more than 3. 1
15, 57, 180, 621, 2061, 6966, 23355, 78597, 264060, 887841, 2984121, 10031526, 33719895, 113349537, 381019140, 1280786661, 4305320181, 14472205686, 48647857635, 163528268877, 549695145420, 1847783097081, 6211265114241 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A184231.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Conjectures: a(n) = 3*a(n-1)+3*a(n-2)-6*a(n-3); G.f.: -3*x*(2*x+1)*(6*x-5) / (6*x^3-3*x^2-3*x+1). - Colin Barker, Sep 26 2014

EXAMPLE

Some solutions for 3X2

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

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

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

CROSSREFS

Sequence in context: A020222 A256867 A158482 * A084815 A240152 A261419

Adjacent sequences:  A184220 A184221 A184222 * A184224 A184225 A184226

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 10 2011

STATUS

approved

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Last modified January 25 19:09 EST 2020. Contains 331249 sequences. (Running on oeis4.)