Find the invalid no.from the following series 3, 7, 15, 31 …

Find the invalid no.from the following series 3, 7, 15, 31 , 63, 127, 257

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

~8 minAnswer checked instantly

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #93536

Stuck? A gentle nudge

No hints for this one.

Something off?

Workspace

Your answer

Checked against the answer in AQuA-RAT.