A258726 Number of length n+4 0..3 arrays with at most one downstep in every 4 consecutive neighbor pairs.

512, 1408, 4184, 12549, 35540, 98676, 281136, 819453, 2358888, 6678576, 18944656, 54386801, 156395364, 446683118, 1271579860, 3632749828, 10409795664, 29790138680, 85049570304, 242860722210, 694569186912, 1987109647472

Offset: 1

Author

R. H. Hardin, Jun 08 2015

Keywords

• nonn

Comments

Column 4 of A258730

Examples

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

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) +30*a(n-4) -72*a(n-5) +58*a(n-6) -16*a(n-7) -31*a(n-8) +36*a(n-9) -10*a(n-10) +a(n-12)