A258728 Number of length n+6 0..3 arrays with at most one downstep in every 6 consecutive neighbor pairs.

2592, 5664, 13720, 35704, 92548, 228081, 526672, 1183616, 2727288, 6597449, 16454876, 40863000, 98379104, 230053160, 534172704, 1260245516, 3043544240, 7443617220, 18093595536, 43272115712, 102190186552, 241107878575

Offset: 1

Author

R. H. Hardin, Jun 08 2015

Keywords

• nonn

Comments

Column 6 of A258730

Examples

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

Links

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

Crossrefs

Cf. A258730

Formula

Empirical: a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +80*a(n-6) -204*a(n-7) +177*a(n-8) -52*a(n-9) -125*a(n-12) +184*a(n-13) -68*a(n-14) +10*a(n-18) -4*a(n-19)