A217885 Number of n element 1..n arrays with each element the minimum of 2 adjacent elements of a permutation of 1..n+1 of n+1 elements

1, 3, 10, 40, 182, 938, 5424, 34788, 244544, 1865144, 15312976, 134495328, 1257334432, 12456693168, 130288665568, 1433829681568

Offset

1,2

Comments

Column 2 of A217891

Links

Table of n, a(n) for n=1..16.

Example

Some solutions for n=4
..2....3....3....1....4....1....1....1....1....1....2....2....1....2....4....3
..1....4....2....2....1....3....2....1....1....3....3....1....1....4....3....3
..1....2....2....2....1....4....3....4....3....2....3....1....3....1....1....2
..4....1....1....4....2....2....4....2....4....2....1....3....3....1....1....1

Crossrefs

Sequence in context: A151077 A300043 A258973 * A216367 A003703 A242651

Adjacent sequences: A217882 A217883 A217884 * A217886 A217887 A217888

Keyword

nonn

Author

R. H. Hardin Oct 14 2012

Status

approved