A194536 Number of lower triangles of an n X n 0..4 array with new values introduced in row major order 0..4 and no element equal to more than one horizontal or vertical neighbor

1, 4, 131, 43785, 79201795, 627974590650, 21399815343394998, 3132305932642809585983, 1969210116072259125767299138

Offset

1,2

Comments

Column 4 of A194540

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for 3X3
..0......0......0......0......0......0......0......0......0......0......0
..1.2....1.0....1.2....1.1....1.0....1.2....1.0....0.1....1.2....1.2....0.1
..2.0.1..2.2.1..0.1.0..0.2.1..2.3.4..3.2.0..0.2.3..1.0.0..2.1.2..0.3.1..1.0.1

Crossrefs

Sequence in context: A113253 A201977 A291172 * A064227 A353794 A204079

Adjacent sequences: A194533 A194534 A194535 * A194537 A194538 A194539

Keyword

nonn

Author

R. H. Hardin Aug 28 2011

Status

approved