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

1,2

Comments

Column 2 of A263703.

Links

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

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)

Example

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

Crossrefs

Cf. A263703.

Sequence in context: A232059 A343889 A263711 * A291409 A263746 A002524

Adjacent sequences: A263694 A263695 A263696 * A263698 A263699 A263700

Keyword

nonn

Author

R. H. Hardin, Oct 24 2015

Status

approved