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A189305 Number of n X 2 array permutations with each element moving zero or one space diagonally, horizontally or vertically. 1
2, 14, 73, 400, 2177, 11854, 64554, 351521, 1914208, 10423761, 56762346, 309097942, 1683185225, 9165743600, 49911830577, 271793641686, 1480045568402, 8059551617921, 43888089440192, 238991507967969, 1301422358761490 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A189312.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 4*a(n-1) +8*a(n-2) -4*a(n-4) +a(n-5).

Empirical g.f.: x*(2 + 2*x - x^2)*(1 + 2*x - x^2) / (1 - 4*x - 8*x^2 + 4*x^4 - x^5). - Colin Barker, May 01 2018

EXAMPLE

Some solutions for 3 X 2:

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

..2..0....2..1....2..3....0..2....4..3....5..2....4..3....4..0....3..5....3..2

..4..5....4..5....5..4....5..4....2..5....4..3....5..2....2..5....2..4....4..5

CROSSREFS

Cf. A189312.

Sequence in context: A002058 A095933 A263218 * A043011 A290698 A138156

Adjacent sequences:  A189302 A189303 A189304 * A189306 A189307 A189308

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 19 2011

STATUS

approved

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Last modified February 17 11:57 EST 2019. Contains 320219 sequences. (Running on oeis4.)