When do Deathclaws start attacking your vault?

I've been playing the Android version for a few days now, and have 33 Dwellers (slow growth FTW?) and I've noticed that I've never been attacked by the Deathclaws that I've heard about.

Do the Deathclaws and other stronger enemies like Raiders with more guns or molerats only show up after a certain number of hours of Vault existence, or perhaps after your Vault reaches a certain number of Dwellers?

Solution 1:

Deathclaws start showing up after you have 60 or more Dwellers in your Vault (the tipping point may be 61). They are attracted by Radio signals and the Door opening.

Solution 2:

According to the Fallout Wiki, Deathclaws start attacking your Vault when you've reached 60 dwellers, or 35 dwellers on Survival mode. The chances of an attack increase as you open your Vault's door, or having an active Radio Room.

Solution 3:

From the Fallout wiki :

According to in-game information, deathclaws are more likely to attack your vault if you open the vault doors and if you have a radio station.

I have no more accurate data for now.

Solution 4:

I did read somewhere that you needed a certain amount of dwellers. Then the variables kick into play.

The variables are: Vault door being opened and Radio Room brodcasts