> I too have been able to get 16 unique products. But getting those last 2 products to differ is a *little* tricky, perhaps, if possible. I can get 17 -- set([2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 27]) -- but not 18 yet. Doug -- Department of Earth Sciences University of Hong Kong