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A224153 Number of n X 3 0..1 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. 1
7, 28, 89, 281, 900, 2935, 9681, 32020, 105937, 350311, 1157860, 3826287, 12643725, 41780500, 138063433, 456233915, 1507641652, 4982061047, 16463412165, 54403960596, 179779885769, 594089193379, 1963189403076, 6487431018743 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A224158.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - a(n-3) - 4*a(n-4) + 14*a(n-5) - 2*a(n-6) - 2*a(n-9).

Empirical g.f.: x*(7 - 9*x^2 - 12*x^3 + 10*x^4 - 2*x^8) / (1 - 4*x + 2*x^2 + x^3 + 4*x^4 - 14*x^5 + 2*x^6 + 2*x^9). - Colin Barker, Aug 28 2018

EXAMPLE

Some solutions for n=3:

..0..1..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..1..0

..1..1..1....1..0..0....1..1..0....0..1..1....1..0..0....1..1..1....1..1..0

..1..1..1....1..1..1....1..1..0....1..1..0....0..1..0....1..1..1....1..0..0

CROSSREFS

Cf. A224158.

Sequence in context: A156928 A117473 A163037 * A276236 A022572 A193654

Adjacent sequences:  A224150 A224151 A224152 * A224154 A224155 A224156

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 31 2013

STATUS

approved

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Last modified June 22 14:32 EDT 2021. Contains 345380 sequences. (Running on oeis4.)