A207146 - OEIS

A207146

Number of (n+1) X 6 0..2 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor.

159, 110, 311, 218, 622, 434, 1238, 866, 2470, 1730, 4934, 3458, 9866, 6914, 19730, 13826, 39458, 27650, 78914, 55298, 157826, 110594, 315650, 221186, 631298, 442370, 1262594, 884738, 2525186, 1769474, 5050370, 3538946, 10100738, 7077890

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OFFSET

1,1

COMMENTS

Column 5 of A207149.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) +2*a(n-2) -2*a(n-3) for n>12.

Empirical g.f.: x*(159 - 49*x - 117*x^2 + 5*x^3 + 2*x^4 - 2*x^5 - 4*x^6 + 4*x^7 - 4*x^8 + 4*x^9 - 4*x^10 + 4*x^11) / ((1 - x)*(1 - 2*x^2)). - Colin Barker, Jun 19 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A207149.

Sequence in context: A159434 A287798 A303811 * A045260 A280967 A192173

Adjacent sequences: A207143 A207144 A207145 * A207147 A207148 A207149

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 15 2012

STATUS

approved