A263678 Number of length n arrays of permutations of 0..n-1 with each element moved by -3 to 3 places and with no two consecutive decreases.

1, 2, 5, 17, 53, 155, 429, 1210, 3457, 9948, 28528, 81636, 233344, 667390, 1909626, 5464861, 15637212, 44741387, 128011961, 366269502, 1047988385, 2998562936, 8579622673, 24548350663, 70238679485, 200969734254, 575022887468

Offset: 1

Author

R. H. Hardin, Oct 23 2015

Keywords

• nonn

Comments

Column 3 of A263683.

Examples

			Some solutions for n=7
..1....0....2....0....0....0....1....0....0....2....0....2....1....1....3....0
..0....4....0....1....2....1....3....2....2....0....1....1....4....3....1....1
..5....5....1....3....3....2....0....1....1....4....5....4....0....4....5....3
..2....6....5....2....1....6....2....3....6....1....2....0....2....0....0....2
..3....1....3....5....4....3....4....5....3....6....6....3....3....2....6....4
..6....2....6....4....5....4....5....4....4....3....3....6....5....5....2....6
..4....3....4....6....6....5....6....6....5....5....4....5....6....6....4....5
		

Links

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

Crossrefs

Cf. A263683.

Formula

Empirical: a(n) = a(n-1) +3*a(n-2) +3*a(n-3) +5*a(n-4) +9*a(n-5) +22*a(n-6) -21*a(n-8) -13*a(n-9) +2*a(n-10) +3*a(n-11) -15*a(n-12) +7*a(n-14) +5*a(n-15) -a(n-16) -2*a(n-17) +3*a(n-18) -a(n-20).