A219628 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 columns, 0..2 2 X n array.

6, 11, 24, 54, 103, 178, 290, 453, 684, 1003, 1433, 2000, 2733, 3664, 4828, 6263, 8010, 10113, 12619, 15578, 19043, 23070, 27718, 33049, 39128, 46023, 53805, 62548, 72329, 83228, 95328, 108715, 123478, 139709, 157503, 176958, 198175, 221258, 246314

Offset

1,1

Comments

Row 2 of A219627.

Links

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

Formula

Empirical: a(n) = (1/8)*n^4 - (11/12)*n^3 + (63/8)*n^2 - (145/12)*n + 3 for n>3.

Conjectures from Colin Barker, Jul 26 2018: (Start)

G.f.: x*(6 - 19*x + 29*x^2 - 16*x^3 - 7*x^4 + 12*x^5 - x^6 - x^7) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>8.

(End)

Example

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

Crossrefs

Cf. A219627.

Sequence in context: A063629 A076496 A354594 * A093027 A109296 A158949

Adjacent sequences: A219625 A219626 A219627 * A219629 A219630 A219631

Keyword

nonn

Author

R. H. Hardin, Nov 24 2012

Status

approved