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A183346 Number of n X 4 binary arrays with each 1 adjacent to exactly one 0 vertically and one 0 horizontally. 1
1, 17, 25, 63, 163, 387, 943, 2289, 5561, 13529, 32865, 79847, 194059, 471603, 1146015, 2784897, 6767617, 16446057, 39965513, 97120103, 236011723, 573532427, 1393741359, 3386931441, 8230584465, 20001149033, 48604804537, 118114565295 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 4 of A183352.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + a(n-2) + 4*a(n-3) + 4*a(n-4) + 3*a(n-5) - a(n-6) - 2*a(n-7) - a(n-8).

Empirical g.f.: x*(1 + 16*x + 7*x^2 + 17*x^3 + 3*x^4 - 10*x^5 - 9*x^6 - x^7) / (1 - x - x^2 - 4*x^3 - 4*x^4 - 3*x^5 + x^6 + 2*x^7 + x^8). - Colin Barker, Mar 28 2018

EXAMPLE

Some solutions for 5 X 4:

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

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

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

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

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

CROSSREFS

Cf. A183352.

Sequence in context: A227238 A294689 A263540 * A166666 A147445 A129910

Adjacent sequences:  A183343 A183344 A183345 * A183347 A183348 A183349

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 04 2011

STATUS

approved

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Last modified September 25 22:19 EDT 2020. Contains 337346 sequences. (Running on oeis4.)