A226437 Number of permutations of {1..n} with fewer than 4 interior elements having values lying between the values of their neighbors.

1, 1, 2, 6, 24, 120, 718, 4914, 37300, 308460, 2748354, 26194542, 265691456, 2856606480, 32449828310, 388371994890, 4885210675692, 64439603536980, 889564376280586, 12827733624005958, 192897097090449208, 3020051018689640760, 49155675298520617182, 830625328754347651746

Offset: 0

Author

R. H. Hardin, Jun 06 2013

Keywords

• nonn

Examples

			Some solutions for n=8:
..3....8....1....8....2....4....2....8....4....5....8....7....6....6....7....2
..7....1....2....5....7....3....5....4....7....7....3....1....3....8....3....8
..1....2....8....6....3....8....4....7....8....1....4....4....7....4....4....6
..2....4....6....3....6....7....8....5....3....2....6....3....5....7....5....3
..8....5....3....1....8....2....1....1....2....4....1....2....4....3....6....5
..6....3....5....2....4....5....3....2....6....3....2....5....8....1....1....1
..4....6....4....7....5....6....6....3....5....8....7....6....2....5....8....4
..5....7....7....4....1....1....7....6....1....6....5....8....1....2....2....7
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..482 (terms n = 1..210 from R. H. Hardin)

Crossrefs

Column 4 of A226441.

Extensions

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