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A259244 Number of (n+1) X (2+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0111. 1
21, 65, 192, 581, 1733, 5216, 15613, 46897, 140568, 421901, 1265269, 3796472, 11387877, 34165857, 102492080, 307483605, 922431077, 2767317200, 8301880013, 24905716177, 74716886152, 224150891421, 672451700885, 2017355772136 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(21 + 2*x - 87*x^2 - 24*x^3) / ((1 - 3*x)*(1 - 4*x^2 - x^3)). - Colin Barker, Dec 24 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 2 of A259250.

Sequence in context: A014641 A259677 A089115 * A020309 A048713 A219814

Adjacent sequences:  A259241 A259242 A259243 * A259245 A259246 A259247

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 22 2015

STATUS

approved

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Last modified October 26 13:09 EDT 2021. Contains 348267 sequences. (Running on oeis4.)