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A183435 Number of n X 2 binary arrays with every 1 having exactly one king-move neighbor equal to 1. 2
2, 7, 13, 28, 69, 149, 330, 755, 1681, 3756, 8457, 18937, 42418, 95183, 213349, 478204, 1072285, 2403885, 5388986, 12082011, 27086537, 60724492, 136139073, 305209713, 684246754, 1534012759, 3439098365, 7710098140, 17285247541, 38751739141 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A183442.

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).

Empirical g.f.: x*(2 + 5*x + 4*x^2) / (1 - x - x^2 - 4*x^3). - Colin Barker, Feb 27 2018

EXAMPLE

Some solutions for 3 X 2:

  1 1   0 1   1 0   0 0   1 1   1 0   0 0   0 0   0 0   0 0

  0 0   1 0   0 1   1 0   0 0   1 0   1 1   0 1   0 0   0 0

  0 0   0 0   0 0   0 1   1 1   0 0   0 0   0 1   0 0   1 1

CROSSREFS

Cf. A183442.

Sequence in context: A180470 A182415 A275491 * A141777 A297883 A215206

Adjacent sequences:  A183432 A183433 A183434 * A183436 A183437 A183438

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 04 2011

STATUS

approved

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Last modified September 24 15:28 EDT 2021. Contains 347643 sequences. (Running on oeis4.)