

A255998


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


1



256, 512, 667, 796, 945, 1134, 1352, 1584, 1831, 2094, 2374, 2672, 2989, 3326, 3684, 4064, 4467, 4894, 5346, 5824, 6329, 6862, 7424, 8016, 8639, 9294, 9982, 10704, 11461, 12254, 13084, 13952, 14859, 15806, 16794, 17824, 18897, 20014, 21176, 22384, 23639
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OFFSET

1,1


COMMENTS

Row 7 of A255992.


LINKS

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


FORMULA

Empirical: a(n) = (1/6)*n^3 + (7/2)*n^2 + (454/3)*n + 64 for n>5.
Empirical g.f.: x*(256  512*x + 155*x^2 + 176*x^3  29*x^4  26*x^5  31*x^6  4*x^7 + 16*x^8) / (1  x)^4.  Colin Barker, Jan 26 2018


EXAMPLE

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


CROSSREFS

Cf. A255992.
Sequence in context: A206206 A206199 A271811 * A309092 A043336 A256822
Adjacent sequences: A255995 A255996 A255997 * A255999 A256000 A256001


KEYWORD

nonn


AUTHOR

R. H. Hardin, Mar 13 2015


STATUS

approved



