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A217995 Number of n X 1 arrays of the minimum or maximum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 1 array. 1
3, 9, 25, 81, 241, 719, 2181, 6543, 19623, 58983, 176995, 531045, 1593739, 4781741, 14346105, 43041933, 129130449, 387399819, 1162223437, 3486708387, 10460197183, 31380761819, 94142587347, 282428344593, 847286292987, 2541861239481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A217999.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + a(n-2) + 2*a(n-3) - 13*a(n-4) - 7*a(n-5) + 3*a(n-6).

Empirical g.f.: x*(3 - 5*x^2 - 9*x^3 - 6*x^4 + 3*x^5) / ((1 - 3*x)*(1 - x^2 - 5*x^3 - 2*x^4 + x^5)). - Colin Barker, Jul 23 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A217999.

Sequence in context: A212352 A198180 A101786 * A246653 A192371 A192465

Adjacent sequences:  A217992 A217993 A217994 * A217996 A217997 A217998

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 17 2012

STATUS

approved

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Last modified June 17 05:30 EDT 2021. Contains 345080 sequences. (Running on oeis4.)