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A224008 Number of n X 4 0..2 arrays with rows nondecreasing and antidiagonals unimodal. 1
15, 225, 2661, 28541, 297859, 3094127, 32148473, 334179881, 3474343713, 36122604265, 375565139165, 3904724751131, 40597113853797, 422084894246843, 4388382334042279, 45625654988950821, 474366234758987515 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A224012.

LINKS

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

FORMULA

Empirical: a(n) = 15*a(n-1) - 58*a(n-2) + 105*a(n-3) + 20*a(n-4) - 183*a(n-5) + 220*a(n-6) + 240*a(n-7).

Empirical g.f.: x*(15 + 156*x^2 + 101*x^3 + 157*x^4 + 460*x^5 + 240*x^6) / (1 - 15*x + 58*x^2 - 105*x^3 - 20*x^4 + 183*x^5 - 220*x^6 - 240*x^7). - Colin Barker, Aug 26 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A224012.

Sequence in context: A223921 A224191 A224349 * A012852 A171289 A262336

Adjacent sequences:  A224005 A224006 A224007 * A224009 A224010 A224011

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 30 2013

STATUS

approved

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Last modified December 6 22:42 EST 2021. Contains 349567 sequences. (Running on oeis4.)