A220045 Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal, diagonal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..3 2 X n array.

10, 13, 25, 50, 90, 152, 249, 397, 618, 941, 1403, 2050, 2938, 4134, 5717, 7779, 10426, 13779, 17975, 23168, 29530, 37252, 46545, 57641, 70794, 86281, 104403, 125486, 149882, 177970, 210157, 246879, 288602, 335823, 389071, 448908, 515930, 590768

Offset

1,1

Comments

Row 2 of A220044.

Links

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

Formula

Empirical: a(n) = (1/120)*n^5 - (1/24)*n^4 + (5/24)*n^3 + (109/24)*n^2 - (1063/60)*n + 39 for n>4.

Conjectures from Colin Barker, Jul 30 2018: (Start)

G.f.: x*(10 - 47*x + 97*x^2 - 105*x^3 + 55*x^4 - 3*x^5 - 6*x^6 - 4*x^7 + 6*x^8 - 2*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..2..2....0..1..0....3..1..1....1..0..0....3..1..1....2..1..2....2..0..2
..2..2..2....0..0..0....3..1..3....1..0..0....3..1..1....2..1..1....2..0..0

Crossrefs

Cf. A220044.

Sequence in context: A111524 A074346 A126973 * A101215 A102249 A195313

Adjacent sequences: A220042 A220043 A220044 * A220046 A220047 A220048

Keyword

nonn

Author

R. H. Hardin, Dec 03 2012

Status

approved