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A202882 Number of nX1 0..2 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor 8
1, 3, 9, 22, 51, 121, 292, 704, 1691, 4059, 9749, 23422, 56268, 135166, 324692, 779977, 1873673, 4500958, 10812237, 25973244, 62393157, 149881402, 360046432, 864906711, 2077686532, 4991036946, 11989513056, 28801314179, 69186771332 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A202889

LINKS

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

T. Mansour, M. Shattuck, Counting Peaks and Valleys in a Partition of a Set , J. Int. Seq. 13 (2010), 10.6.8, Lemma 2.1, k=3, one peak.

FORMULA

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

Empirical: G.f.: -x*(1+3*x^2+x^4)/(-1+3*x-3*x^2+4*x^3-x^4+x^5) . - R. J. Mathar, Jul 09 2017

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Sequence in context: A001628 A099166 A222083 * A054442 A192663 A114697

Adjacent sequences:  A202879 A202880 A202881 * A202883 A202884 A202885

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 25 2011

STATUS

approved

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Last modified February 22 11:16 EST 2018. Contains 299452 sequences. (Running on oeis4.)