What provisional name in Mendeleev's predictions corresponds to technetium?

The provisional name corresponding to technetium was eka-manganese.

Mendeleev predicted in 1871 that an undiscovered element would lie below manganese in his periodic arrangement. He called it eka-manganese, using the Sanskrit-derived prefix eka- to mean “one” position below a known element. He estimated its atomic mass at about 100 and expected it to share chemical similarities with manganese.

Technetium was not isolated until 1937, when Carlo Perrier and Emilio Segrè identified it in molybdenum that had been bombarded with deuterium in a cyclotron built under Ernest Lawrence’s direction. Technetium filled the gap Mendeleev had identified, although its radioactivity helped explain why it had escaped earlier searches.

A common mix-up is eka-silicon, which predicted germanium, while eka-boron predicted scandium and eka-aluminium predicted gallium. The name tri-manganese instead referred to a different later prediction associated with rhenium, not technetium.