

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
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OFFSET

1,5


COMMENTS

a(n) >= ceiling(n(n3)/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



