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

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

Offset

1,2

Comments

Column 7 of A226441

Links

R. H. Hardin, Table of n, a(n) for n = 1..206

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

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

Status

approved