A263592 Number of length n arrays of permutations of 0..n-1 with each element moved by -3 to 3 places and the median of every three consecutive elements nondecreasing.

1, 2, 6, 16, 41, 108, 280, 729, 1908, 4969, 12950, 33796, 88112, 229740, 599191, 1562470, 4074372, 10625188, 27707446, 72253034, 188417568, 491341657, 1281284446, 3341248089, 8713071846, 22721332009, 59251115518, 154510913809

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-2) + 7*a(n-3) + 2*a(n-4) + 4*a(n-5) - a(n-7) - a(n-8).

Empirical g.f.: x*(1 + x + 3*x^2 + x^3 + 3*x^4 + x^5 - x^6 - x^7) / (1 - x - x^2 - 7*x^3 - 2*x^4 - 4*x^5 + x^7 + x^8). - Colin Barker, Jan 02 2019

Example

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

Crossrefs

Column 3 of A263597.

Sequence in context: A068786 A276359 A158920 * A178438 A365548 A143123

Adjacent sequences: A263589 A263590 A263591 * A263593 A263594 A263595

Keyword

nonn

Author

R. H. Hardin, Oct 22 2015

Status

approved