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A208014 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 1 vertically. 1
9, 81, 225, 841, 2304, 6084, 18496, 53824, 150544, 435600, 1263376, 3610000, 10368400, 29899024, 85895824, 246741264, 709902736, 2041232400, 5866947216, 16869853456, 48507419536, 139454446096, 400947305616, 1152814510864 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A208013.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 2*a(n-2) + 10*a(n-3) + 4*a(n-4) - 8*a(n-5) - 16*a(n-6) for n>8.

Empirical g.f.: x*(9 + 72*x + 126*x^2 + 364*x^3 + 167*x^4 - 404*x^5 - 714*x^6 - 148*x^7) / ((1 + 2*x^2 - 4*x^3)*(1 - x - 4*x^2 - 4*x^3)). - Colin Barker, Jun 26 2018

EXAMPLE

Some solutions for n=4:

..0..0..1..0....1..1..1..0....1..1..0..0....1..1..0..0....1..1..1..0

..1..1..1..0....1..1..1..0....0..0..1..1....0..0..1..0....1..0..0..1

..0..0..1..0....1..1..0..0....1..1..0..0....0..1..0..0....0..1..1..0

..1..1..0..0....0..0..1..0....0..0..1..1....0..0..1..0....1..0..0..1

CROSSREFS

Cf. A208013.

Sequence in context: A208114 A208119 A207369 * A208556 A063824 A207560

Adjacent sequences:  A208011 A208012 A208013 * A208015 A208016 A208017

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 22 2012

STATUS

approved

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Last modified May 22 19:59 EDT 2022. Contains 353957 sequences. (Running on oeis4.)