OFFSET
3,3
COMMENTS
Circular permutations are permutations whose indices are from the ring of integers modulo n. For a circular permutation pi, a flattening at position k<n gives a straight permutation which preserves the relative order of pi. For example, the circular permutation (0,2,1) has the flattenings 021, 210, and 102. Note these three flattenings are all not derangements, so a(3) counts (0,2,1).
EXAMPLE
For n=5 the a(5)=3 solutions are (0,3,1,4,2), (0,4,3,2,1), and (0,2,4,1,3).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Isaac Lambert, Jan 06 2013
STATUS
approved