private static IEnumerable <IEnumerable <int> > CreateIndices(int length)
{
return((from p in Enumerable.Range(0, length)
select(
from s in Permutator.CreateIndices(length - 1)
.DefaultIfEmpty(Enumerable.Empty <int>())
select s.Take(p)
.Concat(new[] { length - 1 })
.Concat(s.Skip(p))
))
.SelectMany(i => i));
}
