A220155 Number of 3Xn arrays of the minimum value of corresponding elements and their horizontal or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..2 3Xn array

10, 26, 77, 254, 645, 1413, 2841, 5412, 9905, 17565, 30369, 51437, 85641, 140477, 227277, 362851, 571663, 888660, 1362889, 2062054, 3078183, 4534594, 6594369, 9470566, 13438421, 18849815, 26150305, 35899043, 48791933, 65688403, 87642197

Offset

1,1

Comments

Row 3 of A220153

Links

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

Formula

Empirical: a(n) = (1/362880)*n^9 + (1/40320)*n^8 - (11/60480)*n^7 - (49/2880)*n^6 + (10837/17280)*n^5 - (30473/5760)*n^4 + (1003267/45360)*n^3 + (41353/3360)*n^2 - (594077/2520)*n + 361 for n>6

Example

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

Crossrefs

Sequence in context: A005970 A192254 A368502 * A321311 A051966 A221568

Adjacent sequences: A220152 A220153 A220154 * A220156 A220157 A220158

Keyword

nonn

Author

R. H. Hardin Dec 06 2012

Status

approved