A224369 Number of n X 3 0..2 arrays with rows unimodal and antidiagonals nondecreasing.

22, 218, 1838, 15540, 132236, 1126072, 9588028, 81634704, 695055928, 5917866680, 50386093544, 428998916880, 3652596505952, 31099055733376, 264784589835472, 2254437550085472, 19194805371407680, 163429034985577568

Offset

1,1

Comments

Column 3 of A224374.

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 16*a(n-2) + 30*a(n-3) - 14*a(n-4) + 12*a(n-5).

Empirical g.f.: 2*x*(1 + x + x^2)*(11 - 12*x + 6*x^2) / (1 - 10*x + 16*x^2 - 30*x^3 + 14*x^4 - 12*x^5). - Colin Barker, Aug 30 2018

Example

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

Crossrefs

Cf. A224374.

Sequence in context: A223928 A224052 A224305 * A331882 A008453 A290362

Adjacent sequences: A224366 A224367 A224368 * A224370 A224371 A224372

Keyword

nonn

Author

R. H. Hardin, Apr 05 2013

Status

approved