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.

15, 57, 180, 621, 2061, 6966, 23355, 78597, 264060, 887841, 2984121, 10031526, 33719895, 113349537, 381019140, 1280786661, 4305320181, 14472205686, 48647857635, 163528268877, 549695145420, 1847783097081, 6211265114241

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: A256867 A336251 A158482 * A084815 A240152 A261419

Adjacent sequences: A184220 A184221 A184222 * A184224 A184225 A184226

Keyword

nonn

Author

R. H. Hardin, Jan 10 2011

Status

approved