login
A263710
Number of length n arrays of permutations of 0..n-1 with each element moved by -1 to 1 places and every four consecutive elements having its maximum within 4 of its minimum.
3
1, 2, 3, 5, 8, 11, 17, 25, 37, 57, 84, 127, 191, 284, 429, 641, 961, 1445, 2161, 3246, 4867, 7293, 10948, 16407, 24609, 36913, 55337, 83009, 124472, 186655, 279951, 419784, 629561, 944129, 1415809, 2123305, 3184145, 4775114, 7161091, 10738981, 16104880
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = a(n-1) + a(n-3) - a(n-4) + 2*a(n-5) - a(n-6) + a(n-7).
Empirical g.f.: x*(1 - x + x^2)*(1 + 2*x + 2*x^2 + x^3 + x^4) / (1 - x - x^3 + x^4 - 2*x^5 + x^6 - x^7). - Colin Barker, Jan 02 2019
EXAMPLE
Some solutions for n=7:
..0....0....0....0....1....0....0....1....1....0....1....1....0....0....1....0
..2....1....2....2....0....1....1....0....0....1....0....0....1....1....0....1
..1....2....1....1....2....2....2....2....2....3....2....3....2....3....3....3
..3....3....3....4....3....3....4....4....4....2....3....2....4....2....2....2
..4....4....5....3....4....4....3....3....3....4....4....4....3....4....4....5
..5....6....4....5....6....5....5....6....5....5....5....6....6....6....5....4
..6....5....6....6....5....6....6....5....6....6....6....5....5....5....6....6
CROSSREFS
Column 1 of A263714.
Sequence in context: A227562 A370729 A000511 * A135908 A056891 A065462
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 24 2015
STATUS
approved