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A226437
Number of permutations of {1..n} with fewer than 4 interior elements having values lying between the values of their neighbors.
1
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
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..482 (terms n = 1..210 from R. H. Hardin)
EXAMPLE
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
CROSSREFS
Column 4 of A226441.
Sequence in context: A223905 A374620 A164872 * A224287 A248838 A364231
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jun 06 2013
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Jul 17 2024
STATUS
approved