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A219803 Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal, vertical, diagonal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..3 2 X n array. 1
4, 4, 10, 21, 39, 68, 114, 186, 297, 465, 714, 1075, 1587, 2298, 3266, 4560, 6261, 8463, 11274, 14817, 19231, 24672, 31314, 39350, 48993, 60477, 74058, 90015, 108651, 130294, 155298, 184044, 216941, 254427, 296970, 345069, 399255, 460092, 528178 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A219802.

LINKS

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

FORMULA

Empirical: a(n) = (1/120)*n^5 - (1/8)*n^4 + (29/24)*n^3 - (35/8)*n^2 + (737/60)*n - 12 for n>2.

Conjectures from Colin Barker, Jul 28 2018: (Start)

G.f.: x*(4 - 20*x + 46*x^2 - 59*x^3 + 43*x^4 - 15*x^5 + x^6 + x^7) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>8.

(End)

EXAMPLE

Some solutions for n=3:

..3..3..3....1..0..0....2..0..0....2..2..2....2..1..1....3..0..0....0..0..0

..3..3..3....1..0..0....2..0..0....2..2..2....2..1..1....3..0..0....0..0..0

CROSSREFS

Cf. A219802.

Sequence in context: A095009 A178820 A284784 * A320539 A145598 A320392

Adjacent sequences:  A219800 A219801 A219802 * A219804 A219805 A219806

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 28 2012

STATUS

approved

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Last modified February 26 18:29 EST 2020. Contains 332293 sequences. (Running on oeis4.)