A190928 Number of permutations of n copies of 1..7 introduced in order 1..7 with no element equal to another within a distance of 2

1, 15422, 418539642, 14956351701700, 628262652845622327, 29351897757297625841299, 1478434177099995753393526682, 78758866558881824054985784506762, 4381475477876207136274219572894470265

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..19

Example

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
..3....3....3....3....3....3....3....3....3....3....3....3....3....3....3....3
..4....4....4....4....4....4....4....4....4....1....4....1....4....4....4....4
..5....5....5....1....5....5....5....5....5....4....5....4....5....1....5....1
..6....6....6....2....1....6....6....6....6....5....6....5....6....5....6....2
..2....2....1....5....6....7....3....7....7....2....4....6....4....6....4....5
..7....4....7....6....5....5....7....4....1....6....7....7....5....3....7....6
..4....1....3....4....7....6....4....1....3....7....5....3....7....7....6....3
..3....6....4....5....3....4....6....6....5....4....3....2....1....2....2....7
..5....7....6....7....2....3....5....3....2....5....7....7....6....6....1....4
..6....5....7....6....6....1....1....2....7....7....2....5....3....5....3....5
..1....3....5....3....4....7....7....5....6....3....1....4....2....7....5....7
..7....7....2....7....7....2....2....7....4....6....6....6....7....4....7....6

Crossrefs

Sequence in context: A054838 A255148 A054839 * A345584 A345841 A054840

Adjacent sequences: A190925 A190926 A190927 * A190929 A190930 A190931

Keyword

nonn

Author

R. H. Hardin May 23 2011

Status

approved