A263697 Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and every three consecutive elements having its maximum within 4 of its minimum.

1, 2, 6, 14, 31, 56, 104, 208, 418, 873, 1772, 3545, 7103, 14180, 28572, 57620, 116055, 233735, 469754, 944670, 1900425, 3823544, 7695342, 15483113, 31150656, 62671350, 126083545, 253679744, 510398235, 1026910104, 2066113688, 4156885969

Offset: 1

Author

R. H. Hardin, Oct 24 2015

Keywords

• nonn

Comments

Column 2 of A263703.

Examples

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

Links

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

Crossrefs

Cf. A263703.

Formula

Empirical: a(n) = a(n-1) +a(n-2) +7*a(n-5) +2*a(n-6) +a(n-7) +5*a(n-8) -4*a(n-9) -3*a(n-10) -3*a(n-11) -4*a(n-12) -4*a(n-14) -a(n-15) +3*a(n-16) -a(n-17) +a(n-19)