The Piggyback Sequence
Python 2, 40 39 bytes.

f=lambda x:x&lt;4or.0+f(x-3)+f(x-2)/f(x-1)


Gives True instead of 1, if this isn't allowed we can have this for 42 bytes:

f=lambda x:.0+(x&lt;4or f(x-3)+f(x-2)/f(x-1))


The way it works is pretty straightforward, the only trick is using .0+ to cast the result to a float.