A200884 Number of 0..6 arrays x(0..n+1) of n+2 elements without any interior element greater than both neighbors.

252, 1127, 4977, 22736, 105813, 491533, 2269938, 10462235, 48259083, 222798408, 1028746629, 4749274209, 21922813539, 101196577809, 467142348798, 2156444661242, 9954648966159, 45952741121083, 212127214776309

Offset

1,1

Comments

Column 6 of A200886.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) -21*a(n-2) +56*a(n-3) -70*a(n-4) +126*a(n-5) -84*a(n-6) +120*a(n-7) -45*a(n-8) +55*a(n-9) -11*a(n-10) +12*a(n-11) -a(n-12) +a(n-13).

Empirical g.f.: x*(252 - 637*x + 2380*x^2 - 2548*x^3 + 5706*x^4 - 3276*x^5 + 5620*x^6 - 1820*x^7 + 2630*x^8 - 455*x^9 + 582*x^10 - 42*x^11 + 49*x^12) / (1 - 7*x + 21*x^2 - 56*x^3 + 70*x^4 - 126*x^5 + 84*x^6 - 120*x^7 + 45*x^8 - 55*x^9 + 11*x^10 - 12*x^11 + x^12 - x^13). - Colin Barker, Oct 16 2017

Example

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

Crossrefs

Sequence in context: A046379 A250794 A245858 * A275316 A275315 A184505

Adjacent sequences: A200881 A200882 A200883 * A200885 A200886 A200887

Keyword

nonn

Author

R. H. Hardin, Nov 23 2011

Status

approved