A208018 Number of n X 3 nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal, vertical, diagonal or antidiagonal neighbor (colorings ignoring permutations of colors).

2, 7, 270, 27093, 5252041, 1688298227, 819147302097, 562766251199622, 522687453434959180, 633631710314384052082, 975235769907492737264795, 1863659976446678796423595540, 4341202639797991970260869847084, 12137362722177750192276998364963783

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Example

Some solutions for n=4
..0..1..0....0..1..0....0..1..0....0..1..2....0..1..0....0..1..2....0..1..0
..2..3..2....2..3..2....2..3..2....2..3..0....2..3..2....2..3..4....2..3..2
..4..0..4....0..1..0....4..1..0....4..5..4....0..1..0....5..6..0....0..1..0
..1..2..1....2..3..2....5..2..3....0..1..2....2..3..4....2..3..1....3..2..3

Crossrefs

Column 3 of A208021.

Sequence in context: A295610 A329967 A012942 * A013058 A013097 A037067

Adjacent sequences: A208015 A208016 A208017 * A208019 A208020 A208021

Keyword

nonn

Author

R. H. Hardin, Feb 22 2012

Extensions

Terms a(14) and beyond from Andrew Howroyd, Jun 25 2017

Status

approved