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

Author

R. H. Hardin, Jun 06 2013

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 7 of A226441.

Extensions

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