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A255110 Number of length n+3 0..2 arrays with at most one downstep in every n consecutive neighbor pairs. 1
81, 216, 441, 789, 1302, 2032, 3042, 4407, 6215, 8568, 11583, 15393, 20148, 26016, 33184, 41859, 52269, 64664, 79317, 96525, 116610, 139920, 166830, 197743, 233091, 273336, 318971, 370521, 428544, 493632, 566412, 647547, 737737, 837720, 948273 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A255107.

LINKS

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

FORMULA

Empirical: a(n) = (1/120)*n^5 + (1/4)*n^4 + (59/24)*n^3 + (93/4)*n^2 + (1321/30)*n + 11.

Empirical g.f.: x*(81 - 270*x + 360*x^2 - 237*x^3 + 78*x^4 - 11*x^5) / (1 - x)^6. - Colin Barker, Jan 24 2018

EXAMPLE

Some solutions for n=4:

1   0   2   0   2   0   2   0   2   0   2   0   1   0   0   0

0   2   1   1   0   0   2   2   0   0   0   2   1   0   1   0

0   0   1   1   0   0   2   1   0   0   0   1   2   0   0   0

0   0   1   1   1   0   2   2   1   0   1   1   0   0   0   1

1   1   1   2   1   0   0   2   1   0   1   2   2   1   0   2

1   2   0   0   2   1   0   2   1   0   0   2   2   2   0   2

1   1   2   1   2   2   2   1   2   0   2   1   2   2   0   0

CROSSREFS

Cf. A255107.

Sequence in context: A236728 A236877 A236721 * A062532 A075730 A184068

Adjacent sequences:  A255107 A255108 A255109 * A255111 A255112 A255113

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 14 2015

STATUS

approved

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Last modified September 19 21:34 EDT 2020. Contains 337184 sequences. (Running on oeis4.)