A223790 Number of 3 X n 0..2 arrays with rows, diagonals and antidiagonals unimodal.

27, 729, 8635, 62365, 334230, 1455816, 5425943, 17876443, 53233499, 145612231, 370377451, 884526855, 1998822498, 4301425736, 8862298953, 17560558967, 33594162385, 62253768525, 112071502931, 196491932081, 336258321854

Offset

1,1

Comments

Row 3 of A223789.

Links

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

Formula

Empirical: a(n) = (5051/239500800)*n^12 + (9539/39916800)*n^11 + (86021/21772800)*n^10 + (2861/103680)*n^9 + (1419461/7257600)*n^8 + (453883/403200)*n^7 + (30663023/21772800)*n^6 + (10887469/725760)*n^5 - (167107181/5443200)*n^4 + (16805993/129600)*n^3 - (226950043/831600)*n^2 + (1171756/3465)*n - 185 for n>1.

Example

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

Crossrefs

Cf. A223789.

Sequence in context: A223656 A073537 A016947 * A223976 A167726 A268022

Adjacent sequences: A223787 A223788 A223789 * A223791 A223792 A223793

Keyword

nonn

Author

R. H. Hardin, Mar 27 2013

Status

approved