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A185514 Number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock singular. 1
143, 1489, 12361, 115979, 1058503, 9856209, 91539073, 853020411, 7948563615, 74110312433, 691029158489, 6444134240459, 60095780277207, 560446106259121, 5226693550531025, 48744151344694907, 454588941498687343 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A185521.

LINKS

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

FORMULA

Empirical: a(n) = 12*a(n-1) - 11*a(n-2) - 154*a(n-3) + 224*a(n-4).

Empirical g.f.: x*(143 - 227*x - 3934*x^2 + 6048*x^3) / (1 - 12*x + 11*x^2 + 154*x^3 - 224*x^4). - Colin Barker, Apr 16 2018

EXAMPLE

Some solutions for 5 X 3:

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

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

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

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

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

CROSSREFS

Cf. A185521.

Sequence in context: A156635 A035304 A241924 * A220292 A159054 A135946

Adjacent sequences:  A185511 A185512 A185513 * A185515 A185516 A185517

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 29 2011

STATUS

approved

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Last modified February 16 21:04 EST 2019. Contains 320191 sequences. (Running on oeis4.)