A189274 Number of nX3 array permutations with each element not moved or moved diagonally or antidiagonally by one

1, 9, 45, 225, 1125, 5625, 28125, 140625, 703125, 3515625, 17578125, 87890625, 439453125, 2197265625, 10986328125, 54931640625, 274658203125, 1373291015625, 6866455078125, 34332275390625, 171661376953125, 858306884765625, 4291534423828125, 21457672119140625

Offset

1,2

Comments

Column 3 of A189280

Links

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

Index entries for linear recurrences with constant coefficients, signature (5).

Formula

Empirical: a(n) = 5*a(n-1) for n>2

Apparently, the O.g.f. is x*(1+4x)/(1-5x). - Philippe Deléham, Feb 25 2012

Apparently : a(n) = Sum_{k, 1<=k<=n} A207628(n,k)*2^(k-1). - Philippe Deléham, Feb 25 2012

Example

Some solutions for 4X3
..0..1..4....0..1..4....4..5..2....4..1..2....0..5..2....0..5..2....0..5..2
..3..2..5....3..2..5....3..0..1....3..0..5....3..8..1....7..4..1....3..4..1
.10.11..8....6..7..8...10.11..8....6..9.10....6.11..4...10..3..8....6..7..8
..9..6..7....9.10.11....9..6..7....7..8.11....9.10..7....9..6.11....9.10.11

Crossrefs

Cf. A270567.

Sequence in context: A179855 A255965 A180796 * A270567 A316108 A026092

Adjacent sequences: A189271 A189272 A189273 * A189275 A189276 A189277

Keyword

nonn

Author

R. H. Hardin Apr 19 2011

Status

approved