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A221894 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, without move-in move-out straight through or left turns. 1
3, 31, 266, 2305, 19936, 172624, 1494152, 12933821, 111957318, 969123166, 8388906524, 72615905296, 628576515760, 5441072941952, 47098919537873, 407696835820987, 3529098152699791, 30548517126329090, 264433534642030465 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A221898.

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) + 26*a(n-2) + 45*a(n-3) + 34*a(n-4) - 2*a(n-5) - 4*a(n-6) + a(n-7).

Empirical g.f.: x*(3 + 16*x + 33*x^2 + 34*x^3 - 2*x^4 - 4*x^5 + x^6) / (1 - 5*x - 26*x^2 - 45*x^3 - 34*x^4 + 2*x^5 + 4*x^6 - x^7). - Colin Barker, Aug 11 2018

EXAMPLE

Some solutions for n=3:

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

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

..1..1....1..2....4..0....2..0....1..1....2..0....1..1....2..0....2..0....2..1

CROSSREFS

Cf. A221898.

Sequence in context: A114849 A221899 A242134 * A198964 A212730 A236957

Adjacent sequences:  A221891 A221892 A221893 * A221895 A221896 A221897

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 30 2013

STATUS

approved

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Last modified August 16 07:50 EDT 2022. Contains 356160 sequences. (Running on oeis4.)