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A221625 Number of 3Xn arrays with each row a permutation of 1..n having at least as many downsteps as the preceding row 1
1, 4, 112, 6120, 738150, 148700748, 49096652080, 24099422236160, 17023170538890750, 16517958827528755300, 21433818529290626472948, 36180795747764068402865136, 77856103174007703918070147632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 3 of A221623

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..14

EXAMPLE

Some solutions for n=3

..3..1..2....1..2..3....1..3..2....1..2..3....1..2..3....2..3..1....2..3..1

..1..3..2....3..1..2....3..1..2....1..2..3....2..1..3....2..3..1....1..3..2

..1..3..2....2..3..1....3..2..1....1..2..3....3..2..1....2..1..3....3..1..2

CROSSREFS

Sequence in context: A241798 A158450 A063406 * A013151 A006718 A185320

Adjacent sequences:  A221622 A221623 A221624 * A221626 A221627 A221628

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 21 2013

STATUS

approved

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Last modified May 28 09:09 EDT 2022. Contains 354112 sequences. (Running on oeis4.)