A255990 Number of length n+6 0..1 arrays with at most one downstep in every 6 consecutive neighbor pairs.

64, 98, 156, 257, 428, 705, 1134, 1797, 2848, 4560, 7384, 12021, 19508, 31444, 50432, 80828, 129904, 209549, 338650, 546939, 881612, 1418697, 2281990, 3673412, 5919888, 9546459, 15393334, 24807246, 39956320, 64344494, 103638460, 166985169

Offset

1,1

Comments

Column 6 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) +5*a(n-6) -4*a(n-7).

Empirical g.f.: x*(64 - 30*x + 24*x^2 + 43*x^3 + 70*x^4 + 106*x^5 - 168*x^6) / (1 - 2*x + x^2 - 5*x^6 + 4*x^7). - Colin Barker, Jan 24 2018

Example

Some solutions for n=4:
..0....0....0....0....0....0....0....0....0....1....0....0....0....0....0....0
..0....1....0....0....0....0....1....1....1....1....0....0....0....1....0....1
..0....0....0....0....0....0....1....0....0....1....0....0....1....0....0....0
..0....0....0....0....0....0....0....0....0....1....0....0....0....0....0....1
..0....0....1....1....0....1....0....0....1....1....0....1....0....0....0....1
..0....0....1....0....1....0....0....0....1....1....0....0....0....0....0....1
..0....1....1....0....1....0....0....1....1....0....0....1....0....0....1....1
..0....1....1....0....1....0....0....1....1....0....1....1....0....1....0....1
..0....0....1....1....1....0....0....0....0....0....1....1....0....1....0....1
..0....1....0....1....1....0....0....0....1....0....0....1....0....1....1....0

Crossrefs

Cf. A255992.

Sequence in context: A223086 A175163 A111730 * A104022 A061099 A118488

Adjacent sequences: A255987 A255988 A255989 * A255991 A255992 A255993

Keyword

nonn

Author

R. H. Hardin, Mar 13 2015

Status

approved