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A207148 Number of (n+1) X 8 0..2 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor. 1
315, 218, 619, 434, 1238, 866, 2482, 1730, 4946, 3458, 9874, 6914, 19730, 13826, 39458, 27650, 78914, 55298, 157826, 110594, 315650, 221186, 631298, 442370, 1262594, 884738, 2525186, 1769474, 5050370, 3538946, 10100738, 7077890 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 7 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>14.

Empirical g.f.: x*(315 - 97*x - 229*x^2 + 9*x^3 + 2*x^4 - 2*x^5 + 8*x^6 - 8*x^7 - 16*x^8 + 16*x^9 - 16*x^10 + 16*x^11 - 16*x^12 + 16*x^13) / ((1 - x)*(1 - 2*x^2)). - Colin Barker, Jun 19 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A207149.

Sequence in context: A231021 A104819 A283901 * A210889 A210891 A076648

Adjacent sequences: A207145 A207146 A207147 * A207149 A207150 A207151

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 15 2012

STATUS

approved

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Last modified February 1 08:20 EST 2023. Contains 359992 sequences. (Running on oeis4.)