OFFSET
4,1
COMMENTS
Essentially different ways 1,2,...,n can be placed around a circle so that sums of three consecutive numbers are distinct.
EXAMPLE
a(4)=3 because up to rotation/reflection the only three permutations which work are 1234, 1243, and 1324
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Steve Butler, Feb 08 2012
STATUS
approved