In how many of ways can 4 balls be placed in 3…

In how many of ways can 4 balls be placed in 3 tins if any number of balls can be placed in any tin?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #4339