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A229006 Number of arrays of median of three adjacent elements of some length n+2 0..2 array, with no adjacent equal elements in the latter. 1
3, 7, 15, 31, 57, 105, 193, 353, 653, 1209, 2241, 4161, 7719, 14325, 26581, 49311, 91489, 169729, 314881, 584177, 1083761, 2010609, 3730105, 6920121, 12838307, 23817773, 44187025, 81976335, 152083481, 282147169, 523442893, 971097649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) - a(n-3) + 2*a(n-5) - a(n-6) + 2*a(n-8) - a(n-9) + 2*a(n-11) - 2*a(n-12) + 2*a(n-13).

Empirical g.f.: x*(3 + x + x^2 + 4*x^3 + 2*x^4 + 3*x^6 + x^7 - x^8 + 2*x^9 - 2*x^11 + 2*x^12) / (1 - 2*x + x^3 - 2*x^5 + x^6 - 2*x^8 + x^9 - 2*x^11 + 2*x^12 - 2*x^13). - Colin Barker, Sep 13 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 2 of A229012.

Sequence in context: A222813 A304078 A151338 * A023424 A276647 A006778

Adjacent sequences:  A229003 A229004 A229005 * A229007 A229008 A229009

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 10 2013

STATUS

approved

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Last modified August 4 20:00 EDT 2020. Contains 336202 sequences. (Running on oeis4.)