

A256822


Number of length n+7 0..1 arrays with at most two downsteps in every n consecutive neighbor pairs.


1



256, 512, 1024, 2048, 3728, 6192, 9613, 14168, 20075, 27566, 36888, 48304, 62094, 78556, 98007, 120784, 147245, 177770, 212762, 252648, 297880, 348936, 406321, 470568, 542239, 621926, 710252, 807872, 915474, 1033780, 1163547, 1305568
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OFFSET

1,1


COMMENTS



LINKS



FORMULA

Empirical: a(n) = (1/120)*n^5 + (1/4)*n^4 + (193/8)*n^3  (169/4)*n^2 + (8323/15)*n  1216 for n>5.
Empirical g.f.: x*(256  1024*x + 1792*x^2  1536*x^3 + 400*x^4 + 208*x^5  35*x^6  102*x^7 + 78*x^8  64*x^9 + 28*x^10) / (1  x)^6.  Colin Barker, Jan 21 2018


EXAMPLE

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


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



