A189305 Number of n X 2 array permutations with each element moving zero or one space diagonally, horizontally or vertically.

2, 14, 73, 400, 2177, 11854, 64554, 351521, 1914208, 10423761, 56762346, 309097942, 1683185225, 9165743600, 49911830577, 271793641686, 1480045568402, 8059551617921, 43888089440192, 238991507967969, 1301422358761490

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