A180879 - OEIS

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A180879

Number of permutations p() of 1..n+2 with centered difference p(i+1)-p(i-1) < 0 exactly once.

2

3, 12, 50, 160, 525, 1540, 4662, 13104, 38346, 105336, 303732, 823680, 2361645, 6357780, 18208190, 48814480, 139952670, 374315656, 1075431084, 2872519104, 8273365282, 22082137896, 63760878300, 170112213600, 492371090100

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OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n=1..100

PROG

(bc) /* See A180887 */

CROSSREFS

Column 2 of A180887.

Sequence in context: A002179 A224659 A034541 * A391835 A180283 A037765

Adjacent sequences: A180876 A180877 A180878 * A180880 A180881 A180882

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 23 2010

STATUS

approved