A226440 Number of permutations of {1..n} with fewer than 7 interior elements having values lying between the values of their neighbors.

1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362878, 3627778, 39830282, 475089392, 6094561180, 83333937940, 1205398303180, 18331873363480, 291706615484450, 4838414115229430, 83404373736108502, 1490681666580459304, 27572241018065482032, 526959942343051879032

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..480 (terms n = 1..206 from R. H. Hardin)

Example

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

Crossrefs

Column 7 of A226441.

Sequence in context: A054873 A324075 A193936 * A248841 A072132 A230231

Adjacent sequences: A226437 A226438 A226439 * A226441 A226442 A226443

Keyword

nonn

Author

R. H. Hardin, Jun 06 2013

Extensions

a(0)=1 prepended by Alois P. Heinz, Jul 17 2024

Status

approved