A200883 Number of 0..5 arrays x(0..n+1) of n+2 elements without any interior element greater than both neighbors.

161, 636, 2507, 10213, 42182, 173606, 710976, 2908797, 11911516, 48807427, 199987737, 819315100, 3356387171, 13749952752, 56330082115, 230771042950, 945410224602, 3873094298871, 15867039092263, 65003096433432

Offset

1,1

Comments

Column 5 of A200886.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -15*a(n-2) +35*a(n-3) -35*a(n-4) +56*a(n-5) -28*a(n-6) +36*a(n-7) -9*a(n-8) +10*a(n-9) -a(n-10) +a(n-11).

Empirical g.f.: x*(161 - 330*x + 1106*x^2 - 924*x^3 + 1884*x^4 - 792*x^5 + 1252*x^6 - 264*x^7 + 355*x^8 - 30*x^9 + 36*x^10) / (1 - 6*x + 15*x^2 - 35*x^3 + 35*x^4 - 56*x^5 + 28*x^6 - 36*x^7 + 9*x^8 - 10*x^9 + x^10 - x^11). - Colin Barker, Oct 16 2017

Example

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

Crossrefs

Sequence in context: A159545 A157337 A200869 * A196635 A196640 A232072

Adjacent sequences: A200880 A200881 A200882 * A200884 A200885 A200886

Keyword

nonn

Author

R. H. Hardin, Nov 23 2011

Status

approved