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A221201 Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2. 1
0, 9, 10, 196, 720, 6400, 34272, 242064, 1460368, 9610000, 60194160, 387459856, 2455717680, 15698085264, 99863349040, 636989149456, 4056917039280, 25859869267600, 164758872493872, 1049992515273744, 6690497356781488 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A221200.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..86

FORMULA

Empirical: a(n) = 7*a(n-1) + 14*a(n-2) - 126*a(n-3) + 504*a(n-5) - 224*a(n-6) - 448*a(n-7) + 256*a(n-8).

Empirical g.f.: x^2*(9 - 53*x + 342*x^3 - 124*x^4 - 448*x^5 + 256*x^6) / ((1 - 2*x)*(1 + 2*x)*(1 - 7*x + 4*x^2)*(1 - 14*x^2 + 16*x^4)). - Colin Barker, Aug 04 2018

EXAMPLE

Some solutions for n=3:

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

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

CROSSREFS

Cf. A221200.

Sequence in context: A336690 A041177 A041178 * A119159 A041415 A103869

Adjacent sequences:  A221198 A221199 A221200 * A221202 A221203 A221204

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 04 2013

STATUS

approved

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Last modified October 27 06:31 EDT 2021. Contains 348271 sequences. (Running on oeis4.)