japanjot said:
Vin<<< why +vin at gate? sorry m lil confused
Misunderstanding:
Not connected to +vin, but to the outputs of your 4017 counter/decoder! This only means the active output level is (nearly) equal to +vin.
A series resistor between the 4017 outputs and the MOSFET gate limits the load current to the high input cap of the MOSFET. It's sort of a safety feature for the 4017, also against the (unlikely) case of drain-gate shortage of the MOSFET, i.e. not absolutely necessary, however recommended. Any value between 100Ω and 10kΩ is ok; for your LED application I'd suggest 1kΩ.