A219715 Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..3 2 X n array.

10, 13, 45, 125, 283, 561, 1030, 1776, 2916, 4610, 7073, 10587, 15513, 22303, 31512, 43810, 59994, 81000, 107915, 141989, 184647, 237501, 302362, 381252, 476416, 590334, 725733, 885599, 1073189, 1292043, 1545996, 1839190, 2176086, 2561476

Offset

1,1

Comments

Row 2 of A219714.

Links

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

Formula

Empirical: a(n) = (1/10)*n^5 - (53/24)*n^4 + (117/4)*n^3 - (4099/24)*n^2 + (10233/20)*n - 594 for n>4.

Conjectures from Colin Barker, Jul 27 2018: (Start)

G.f.: x*(10 - 47*x + 117*x^2 - 150*x^3 + 98*x^4 - 27*x^5 + 16*x^6 - 31*x^7 + 30*x^8 - 4*x^9) / (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>10.

(End)

Example

Some solutions for n=3:
..2..1..1....0..0..0....2..0..0....2..2..1....2..1..1....2..0..0....2..0..0
..2..1..3....0..0..0....2..0..2....1..1..1....1..0..0....0..0..0....1..0..1

Crossrefs

Cf. A219714.

Sequence in context: A219829 A062370 A069960 * A154142 A219804 A108761

Adjacent sequences: A219712 A219713 A219714 * A219716 A219717 A219718

Keyword

nonn

Author

R. H. Hardin, Nov 26 2012

Status

approved