A194889 Number of lower triangles of an n X n 0..4 array with new values introduced in row major order 0..4 and no two horizontal or vertical neighbors of any element equal

1, 3, 33, 1620, 136080, 17962560, 3751608960, 1233597237120, 641473938397440, 526921921428975360

Offset

1,2

Comments

Column 4 of A194893

Links

Table of n, a(n) for n=1..10.

Example

Some solutions for 4X4
..0........0........0........0........0........0........0........0
..1.2......0.1......1.2......1.1......0.1......1.2......0.1......1.1
..3.0.1....2.3.4....1.3.0....2.3.4....2.1.3....1.2.3....2.1.0....2.3.3
..4.0.3.2..2.0.1.1..0.4.2.1..2.0.1.1..2.0.4.4..4.0.1.4..2.3.0.1..2.0.4.2

Crossrefs

Sequence in context: A113111 A118188 A342170 * A126675 A038694 A319750

Adjacent sequences: A194886 A194887 A194888 * A194890 A194891 A194892

Keyword

nonn

Author

R. H. Hardin Sep 04 2011

Status

approved