The lightest isotopes of copernicium have been synthesized by direct fusion between two lighter nuclei and as decay products (except for Cn, which is not known to be a decay product), while the heavier isotopes are only known to be produced by decay of heavier nuclei. The heaviest isotope produced by direct fusion is Cn; the three heavier isotopes, Cn, Cn, and Cn, have only been observed as decay products of elements with larger atomic numbers.