don’t ask why it just came in my head

QuandarySo you have a fair coin that you found on the ground,

or at least that’s what everyone says.

But on each of N times that you’ve tossed it around,

you see every flip has been heads.For which value of N should you start to suspect

that the coin isn’t actually fair?

For which values of N can you firmly declare

that the tails side is not even there?