A190932 Number of permutations of n copies of 1..8 introduced in order 1..8 with no element equal to another within a distance of 1.

1, 721315, 1133879136649, 2536823683737613858, 6945222145021508480249929, 21671513613423101256198918372909, 74115215422015289392187745053216373265, 271259741131895052775392614041761701799270286

Offset: 1

Author

R. H. Hardin, May 23 2011

Keywords

• nonn

Examples

			Some solutions for n=2
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..2....2....2....2....2....2....2....2....2....2....2....2....2....2....2....2
..1....3....3....1....1....1....3....1....3....3....1....1....1....1....3....1
..3....1....1....3....3....3....1....3....1....1....3....3....3....3....1....2
..4....4....4....4....4....4....4....4....2....4....4....4....4....4....4....3
..5....5....5....3....5....5....5....5....3....5....5....5....2....5....5....4
..6....4....3....5....6....6....6....4....4....3....4....6....5....6....2....5
..5....6....6....6....7....7....2....6....5....6....5....7....6....5....6....6
..6....7....7....7....5....2....3....7....6....5....6....8....7....7....7....7
..3....8....8....8....6....8....5....8....7....2....7....7....5....8....3....8
..2....5....2....7....8....6....7....3....4....7....2....5....8....3....8....3
..7....2....6....8....2....3....6....6....6....6....6....2....3....6....4....5
..8....8....7....4....3....4....8....5....8....7....7....3....7....4....6....7
..4....3....4....6....4....5....7....8....5....8....8....4....4....2....7....4
..8....7....5....5....8....8....8....2....7....4....3....8....8....7....8....8
..7....6....8....2....7....7....4....7....8....8....8....6....6....8....5....6
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..149 (terms 1..20 from R. H. Hardin)

Crossrefs

Column k=8 of A322013.

Cf. A000012, A190917, A190918, A190920, A190923, A190927, A321987.

Formula

a(n) ~ 2 * 7^(8*n-2) / (1215 * sqrt(3) * Pi^(7/2) * n^(7/2)). - Vaclav Kotesovec, Nov 24 2018