A226438 Number of permutations of {1..n} with fewer than 5 interior elements having values lying between the values of their neighbors.

1, 1, 2, 6, 24, 120, 720, 5038, 40066, 353556, 3399246, 35142546, 387129588, 4515261680, 55502974820, 716557285110, 9689420220510, 136922907564972, 2018121531850482, 30972340185946810, 494190208052390752, 8186609585709287112, 140620153367124829272

Offset: 0

Author

R. H. Hardin, Jun 06 2013

Keywords

• nonn

Examples

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

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..481 (terms n = 1..210 from R. H. Hardin)

Crossrefs

Column 5 of A226441.

Extensions

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