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

Author

R. H. Hardin Apr 19 2011

Keywords

• nonn

Comments

Column 3 of A189280

Examples

			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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200
• Index entries for linear recurrences with constant coefficients, signature (5).

Crossrefs

Cf. A270567.

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