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A217878 Number of n-element 0..2 arrays with each element the minimum of 3 adjacent elements of a random 0..2 array of n+2 elements. 3
3, 9, 22, 46, 91, 183, 383, 819, 1749, 3699, 7772, 16316, 34325, 72349, 152573, 321621, 677623, 1427389, 3006930, 6335210, 13348399, 28125235, 59258363, 124851495, 263048937, 554220135, 1167698552, 2460253944, 5183565225, 10921353721 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A228461 and A217883 for more information about the definition.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) -3*a(n-2) +a(n-3) +3*a(n-4) -a(n-5) +a(n-6) +a(n-7).

Empirical g.f.: x*(1 + x^2 + x^3)*(3 + x^2 + x^3) / ((1 - x + x^2 + x^3)*(1 - 2*x - x^4)). - Colin Barker, Feb 23 2018

EXAMPLE

Some solutions for n=4:

..0....1....0....0....2....1....1....1....0....1....2....0....0....0....1....0

..0....1....2....0....1....1....2....2....1....1....2....1....1....0....2....1

..0....2....0....0....1....1....0....2....2....0....2....1....1....2....1....2

..2....2....0....1....1....1....0....1....1....0....1....1....2....2....1....0

CROSSREFS

Column 3 of A217954. Also a column of A217883. Cf. A217954.

Sequence in context: A217881 A217880 A217879 * A192389 A187053 A001937

Adjacent sequences: A217875 A217876 A217877 * A217879 A217880 A217881

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 14 2012

STATUS

approved

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Last modified February 5 03:48 EST 2023. Contains 360082 sequences. (Running on oeis4.)