A258729 Number of length n+7 0..3 arrays with at most one downstep in every 7 consecutive neighbor pairs.

5115, 10280, 22866, 55660, 138196, 331584, 752180, 1607656, 3343894, 7100132, 15867680, 37057120, 87647408, 203774064, 457583316, 996246248, 2145967651, 4684383672, 10501666108, 24080284440, 55579151729, 126886388888

Offset: 1

Author

R. H. Hardin, Jun 08 2015

Keywords

• nonn

Comments

Column 7 of A258730

Examples

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

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) +116*a(n-7) -303*a(n-8) +268*a(n-9) -80*a(n-10) -206*a(n-14) +320*a(n-15) -125*a(n-16) +20*a(n-21) -10*a(n-22)