What number comes next in this Number series

What number comes next in this Number series. 8 5 5 3 4 4 6 ? *Hint: check calende

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 #60436