A180069 - OEIS

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A180069

Number of permutations of 1..n with the sum of squared adjacent differences < n*(n-1)/2

0, 2, 2, 6, 34, 132, 448, 1986, 8422, 39902, 195946, 1024366, 5505428, 31185644, 183904498, 1119250852, 7025176096, 45663175776, 306194071810, 2107066845486, 14874884490258, 107949634637898

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OFFSET

2,2

LINKS

Table of n, a(n) for n=2..23.

CROSSREFS

Cf. A180068.

Sequence in context: A117394 A267073 A003308 * A032185 A179236 A002027

Adjacent sequences: A180066 A180067 A180068 * A180070 A180071 A180072

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 09 2010

EXTENSIONS

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

a(19)-a(23) from Martin Ehrenstein, Nov 12 2023

STATUS

approved