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A224129 Number of n X 4 0..1 arrays with rows nondecreasing and antidiagonals unimodal. 1
5, 25, 106, 419, 1635, 6392, 25047, 98221, 385194, 1510527, 5923295, 23227112, 91080915, 357157713, 1400531394, 5491938683, 21535675531, 84448377880, 331149514687, 1298544789829, 5092015833594, 19967447759719, 78298847269031 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A224133.

LINKS

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

FORMULA

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

Empirical g.f.: x*(5 + 6*x^2 + 4*x^3) / (1 - 5*x + 5*x^2 - 2*x^3 - 4*x^4). - Colin Barker, Aug 27 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A224133.

Sequence in context: A264018 A067971 A266424 * A111641 A074419 A247105

Adjacent sequences:  A224126 A224127 A224128 * A224130 A224131 A224132

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 31 2013

STATUS

approved

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Last modified May 14 04:48 EDT 2021. Contains 343872 sequences. (Running on oeis4.)