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A184766 Number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock singular. 1
424, 8272, 108496, 1792144, 27993232, 454774672, 7339536784, 119205236368, 1934859805840, 31437977902480, 510797840746384, 8300795694017680, 134894624057920144, 2192213833325394832, 35626484733088902544 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A184773.

LINKS

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

FORMULA

Empirical: a(n) = 20*a(n-1) - 19*a(n-2) - 792*a(n-3) + 1800*a(n-4).

Empirical g.f.: 8*x*(53 - 26*x - 6111*x^2 + 14400*x^3) / (1 - 20*x + 19*x^2 + 792*x^3 - 1800*x^4). - Colin Barker, Apr 15 2018

EXAMPLE

Some solutions for 5 X 3:

..0..0..0....2..0..0....0..0..0....0..0..0....2..0..0....2..0..0....2..0..0

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

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

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

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

CROSSREFS

Cf. A184773.

Sequence in context: A202772 A220541 A091292 * A250377 A250342 A232359

Adjacent sequences:  A184763 A184764 A184765 * A184767 A184768 A184769

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 21 2011

STATUS

approved

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Last modified November 17 23:26 EST 2019. Contains 329242 sequences. (Running on oeis4.)