OFFSET
5,1
COMMENTS
Essentially different ways that 1,2,...,n can be placed around a circle so that the sums of three consecutive terms are all distinct.
EXAMPLE
a(6)=8 because up to rotation/reflection the only three permutations which work are 123465, 123546, 124653, 125364, 126543, 132456, 132645, 136524.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Steve Butler, Feb 08 2012
STATUS
approved