Information on mass chains and nuclides available on this website:

WWW TUNL

The light nuclei observed, by particle-identification techniques, to be emitted in the 5.5 GeV proton bombardment of uranium do not include ¹³Be. It is therefore particle unstable (PO68B). (GA66C) predict that ¹³Be is unbound with respect to ¹²Be + n by 2.70 MeV.