A263711 Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and every four consecutive elements having its maximum within 4 of its minimum.

1, 2, 6, 14, 31, 34, 39, 46, 64, 104, 161, 249, 385, 561, 845, 1254, 1871, 2833, 4228, 6359, 9545, 14273, 21453, 32133, 48184, 72323, 108363, 162592, 243817, 365545, 548369, 822181, 1233053, 1849282, 2772959, 4158841, 6236608, 9352579, 14026153

Offset

1,2

Links

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

Formula

Empirical: a(n) = a(n-1) + a(n-3) - a(n-4) + 2*a(n-5) - a(n-6) + a(n-7) for n>18.

Empirical g.f.: x*(1 + x + 4*x^2 + 7*x^3 + 16*x^4 - 3*x^5 - 6*x^6 - 21*x^7 - 9*x^8 - 19*x^9 - x^10 - 5*x^11 + 9*x^12 - 2*x^13 + 6*x^14 - 9*x^15 - 4*x^17) / (1 - x - x^3 + x^4 - 2*x^5 + x^6 - x^7). - Colin Barker, Jan 02 2019

Example

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

Crossrefs

Column 2 of A263714.

Sequence in context: A237623 A232059 A343889 * A263697 A291409 A263746

Adjacent sequences: A263708 A263709 A263710 * A263712 A263713 A263714

Keyword

nonn

Author

R. H. Hardin, Oct 24 2015

Status

approved