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A180071 Number of permutations of {1..n} with the sum of squared adjacent differences < n*(n+1)/2. 1
0, 1, 2, 6, 12, 24, 98, 344, 1236, 5332, 23772, 110962, 547714, 2840028, 15439466, 87299850, 512569668, 3111575102, 19577613014, 127331688104 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

CROSSREFS

Cf. A180070.

Sequence in context: A163895 A309016 A302652 * A034882 A175943 A228816

Adjacent sequences:  A180068 A180069 A180070 * A180072 A180073 A180074

KEYWORD

nonn,hard,more

AUTHOR

R. H. Hardin, Aug 09 2010

EXTENSIONS

a(17)-a(18) from Donovan Johnson, Oct 11 2010

a(19) from Bert Dobbelaere, Aug 31 2020

a(0)-a(1) from Alois P. Heinz, Sep 02 2020

STATUS

approved

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Last modified March 5 14:33 EST 2021. Contains 341823 sequences. (Running on oeis4.)