

A255990


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


1



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
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OFFSET

1,1


COMMENTS



LINKS



FORMULA

Empirical: a(n) = 2*a(n1) a(n2) +5*a(n6) 4*a(n7).
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



KEYWORD

nonn


AUTHOR



STATUS

approved



