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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, 2, 6, 24, 120, 718, 4914, 37300, 308460, 2748354, 26194542, 265691456, 2856606480, 32449828310, 388371994890, 4885210675692, 64439603536980, 889564376280586, 12827733624005958, 192897097090449208 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 4 of A226441

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Sequence in context: A177524 A223905 A164872 * A224287 A248838 A052398

Adjacent sequences: A226434 A226435 A226436 * A226438 A226439 A226440

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 06 2013

STATUS

approved

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Last modified November 29 15:30 EST 2022. Contains 358431 sequences. (Running on oeis4.)