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A255989 Number of length n+5 0..1 arrays with at most one downstep in every 5 consecutive neighbor pairs. 1
42, 68, 114, 196, 337, 568, 945, 1574, 2645, 4476, 7568, 12736, 21365, 35852, 60308, 101608, 171148, 287940, 484045, 813826, 1369115, 2304172, 3877545, 6523278, 10972180, 18456064, 31049291, 52240182, 87891550, 147861804, 248739774 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 5 of A255992.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) -a(n-2) +4*a(n-5) -3*a(n-6).

Empirical g.f.: x*(42 - 16*x + 20*x^2 + 36*x^3 + 59*x^4 - 78*x^5) / ((1 + x - x^3)*(1 - 3*x + 4*x^2 - 3*x^3)). - Colin Barker, Jan 24 2018

EXAMPLE

Some solutions for n=4:

..1....0....1....0....0....1....0....0....0....0....0....0....1....1....0....1

..1....1....0....1....0....0....0....1....1....0....0....1....1....1....1....0

..0....1....1....0....1....0....1....0....0....1....0....0....0....0....0....0

..0....1....1....1....1....0....1....0....0....0....0....0....0....0....0....1

..1....1....1....1....1....0....1....0....1....0....0....0....0....1....0....1

..1....1....1....1....1....1....1....0....1....0....0....1....1....1....0....1

..1....1....0....1....0....1....1....0....1....1....1....1....1....1....1....1

..0....1....0....0....0....0....0....1....1....1....0....0....1....0....0....1

..0....1....0....1....0....0....0....0....1....0....0....0....0....1....1....0

CROSSREFS

Cf. A255992.

Sequence in context: A193343 A118074 A115957 * A192274 A291319 A226168

Adjacent sequences:  A255986 A255987 A255988 * A255990 A255991 A255992

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 13 2015

STATUS

approved

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Last modified October 17 11:44 EDT 2019. Contains 328108 sequences. (Running on oeis4.)