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A282847 Given n people seated at a table, a(n) gives the minimum number of swaps that must occur in order for everybody to have sat next to every other person. 0
0, 0, 0, 1, 3, 4, 4, 6, 8, 10, 12, 14, 17, 20 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

a(n) >= ceiling(n(n-3)/8).

LINKS

Table of n, a(n) for n=1..14.

Math Stack Exchange, Making Friends around a Circular Table

EXAMPLE

For n = 7 the a(7) = 4 swaps are:

(1) 1 swaps with 4,

(2) 1 swaps with 5,

(3) 3 swaps with 6, and then

(4) 2 swaps with 6.

CROSSREFS

Sequence in context: A161359 A224212 A078490 * A047877 A280448 A100692

Adjacent sequences:  A282844 A282845 A282846 * A282848 A282849 A282850

KEYWORD

nonn,hard,more

AUTHOR

Peter Kagey, Feb 24 2017

EXTENSIONS

a(13) and a(14) added by Dmitry Kamenetsky, Feb 26 2017

STATUS

approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)