A207868 T(n,k)=Number of n X k nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or vertical neighbor (colorings ignoring permutations of colors).
1, 1, 1, 2, 4, 2, 5, 34, 34, 5, 15, 500, 2052, 500, 15, 52, 10900, 278982, 278982, 10900, 52, 203, 322768, 68162042, 455546040, 68162042, 322768, 203, 877, 12297768, 26419793726, 1625686993918, 1625686993918, 26419793726, 12297768, 877
Offset: 1
Examples
Some solutions for n=5 k=3 ..0..1..0....0..1..2....0..1..0....0..1..0....0..1..2....0..1..0....0..1..0 ..1..0..1....1..0..3....1..0..1....1..0..1....1..2..0....1..0..1....1..0..1 ..0..1..0....0..1..0....0..1..0....2..1..0....0..1..2....0..2..3....0..1..2 ..1..0..1....1..0..1....1..0..1....0..2..3....1..0..1....1..0..1....1..0..1 ..0..1..0....0..1..0....2..1..0....1..3..0....2..1..0....0..1..0....0..1..0
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..231 (terms 1..49 from R. H. Hardin)
- Eric Weisstein's World of Mathematics, Grid Graph.
- Eric Weisstein's World of Mathematics, Vertex Coloring.
- Wikipedia, Graph Coloring.
Comments