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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 5 of A226441

LINKS

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

EXAMPLE

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

CROSSREFS

Sequence in context: A193935 A177534 A164873 * A248839 A052399 A177553

Adjacent sequences: A226435 A226436 A226437 * A226439 A226440 A226441

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 06 2013

STATUS

approved

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Last modified December 9 17:46 EST 2022. Contains 358703 sequences. (Running on oeis4.)