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A221484 Number of 2 X n arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without consecutive moves in the same direction. 1
0, 4, 8, 73, 292, 1713, 8235, 43733, 220672, 1142790, 5840082, 30047605, 154064032, 791329272, 4060908537, 20849136414, 107016685715, 549372170263, 2820041046796, 14476302849381, 74310986678816, 381462539353767 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A221483.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 17*a(n-2) + 22*a(n-3) + a(n-4) - 14*a(n-5) - 2*a(n-6) + a(n-7).

Empirical g.f.: x^2*(1 - x)*(4 + 8*x + 5*x^2) / ((1 + 3*x + x^2)*(1 - 4*x - 6*x^2 + 5*x^4 - x^5)). - Colin Barker, Aug 06 2018

EXAMPLE

Some solutions for n=3:

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

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

CROSSREFS

Cf. A221483.

Sequence in context: A274461 A206346 A240503 * A338314 A288956 A236284

Adjacent sequences:  A221481 A221482 A221483 * A221485 A221486 A221487

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 17 2013

STATUS

approved

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Last modified October 31 19:00 EDT 2020. Contains 338111 sequences. (Running on oeis4.)