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A221126 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor. 1
1, 21, 200, 1950, 19005, 185164, 1803949, 17574675, 171218008, 1668058947, 16250746331, 158319795778, 1542400400537, 15026541578483, 146393213915408, 1426207951308175, 13894558811577567, 135365087812821450 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A221125.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..88

FORMULA

Empirical: a(n) = 11*a(n-1) - 11*a(n-2) - 12*a(n-3) - 2*a(n-4) for n>6.

Empirical g.f.: x*(1 + 10*x - 20*x^2 - 7*x^3 + 9*x^4 + x^5) / (1 - 11*x + 11*x^2 + 12*x^3 + 2*x^4). - Colin Barker, Aug 04 2018

EXAMPLE

Some solutions for n=3:

..0..1..0....1..0..2....1..2..0....1..2..0....0..3..1....1..1..1....0..1..0

..2..3..0....0..1..2....2..0..1....1..2..0....0..0..2....1..0..2....2..1..2

CROSSREFS

Cf. A221125.

Sequence in context: A058086 A270957 A159857 * A239418 A337897 A341399

Adjacent sequences:  A221123 A221124 A221125 * A221127 A221128 A221129

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 02 2013

STATUS

approved

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Last modified May 27 03:13 EDT 2022. Contains 354093 sequences. (Running on oeis4.)