A198982 T(n,k) = number of n X k 0..5 arrays with values 0..5 introduced in row major order and no element equal to any horizontal or vertical neighbor.

1, 1, 1, 2, 4, 2, 5, 34, 34, 5, 15, 481, 1835, 481, 15, 52, 8731, 146286, 146286, 8731, 52, 202, 174454, 12662226, 53082012, 12662226, 174454, 202, 855, 3603244, 1112962873, 19622872903, 19622872903, 1112962873, 3603244, 855, 3845, 75251971

Offset

1,4

Comments

Number of colorings of the grid graph P_n X P_k using a maximum of 6 colors up to permutation of the colors. - Andrew Howroyd, Jun 26 2017

Links

Andrew Howroyd, Table of n, a(n) for n = 1..325 (terms 1..111 from R. H. Hardin)

Example

Table starts
.....1...........1.................2........................5
.....1...........4................34......................481
.....2..........34..............1835...................146286
.....5.........481............146286.................53082012
....15........8731..........12662226..............19622872903
....52......174454........1112962873............7267830860056
...202.....3603244.......98102456246.........2692353648978984
...855....75251971.....8651794282083.......997397244990907738
..3845..1577395861...763087851014929....369492074075459555844
.18002.33105096904.67305520316532514.136880688981914387733120
...
Some solutions with all values from 0 to 5 for n=6, k=4:
..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1
..1..2..3..0....1..2..3..0....1..2..3..0....1..2..3..0....1..2..3..0
..0..3..0..1....0..3..0..1....0..3..0..1....0..3..0..1....0..3..0..1
..2..0..3..0....1..0..3..0....1..0..3..0....1..0..3..0....1..0..3..0
..1..2..0..2....4..1..0..1....3..1..0..4....3..4..2..1....3..4..2..5
..4..5..2..1....5..4..2..4....5..2..3..1....1..5..1..5....5..1..5..2

Crossrefs

Columns 1-7 are A056272(n-1), A198976, A198977, A198978, A198979, A198980, A198981.

Main diagonal is A198975.

Cf. A207997 (3 colorings), A198715 (4 colorings), A198906 (5 colorings), A222281 (labeled 6 colorings), A198723 (7 colorings), A198914 (8 colorings), A207868 (unlimited).

Sequence in context: A198715 A216663 A198906 * A198723 A198914 A207868

Adjacent sequences: A198979 A198980 A198981 * A198983 A198984 A198985

Keyword

nonn,tabl

Author

R. H. Hardin, Nov 01 2011

Status

approved