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A205993 Number of (n+1)X4 0..2 arrays with the number of clockwise edge increases in every 2X2 subblock equal to two, and every 2X2 determinant nonzero 1
330, 2712, 22612, 189430, 1588523, 13324720, 111764603, 937463556, 7863232776, 65955006340, 553215476117, 4640243767418, 38921297804723, 326462877927870, 2738295489854762, 22968191962261382, 192651906939967689 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A205998

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) +40*a(n-2) -160*a(n-3) -206*a(n-4) +1227*a(n-5) +360*a(n-6) -5565*a(n-7) +4196*a(n-8) +4799*a(n-9) -3146*a(n-10) -3968*a(n-11) -1311*a(n-12) -636*a(n-13) -64*a(n-14) +210*a(n-15) +588*a(n-16) +228*a(n-17) +32*a(n-18) -16*a(n-19) for n>20

EXAMPLE

Some solutions for n=4

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

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

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

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

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

CROSSREFS

Sequence in context: A237189 A064262 A126997 * A027807 A104476 A140908

Adjacent sequences:  A205990 A205991 A205992 * A205994 A205995 A205996

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 02 2012

STATUS

approved

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Last modified May 28 15:33 EDT 2020. Contains 334684 sequences. (Running on oeis4.)