How to design this synchronous circuit? I have seen this model question on synchronous circuit , but i could not understand the logic,  can anyone please help me?

"Develop the state diagram for a synchronous sequential circuit which will recognize the bit sequence 1101 (ie, every time the sequence 1101 is detected in the input bit stream, the circuit has to output a 1 and otherwise a 0)."

What is the question here?? do we have consider all possible combinations ( 2^4 - 16 ) to do this ? if so , according to the question , do we have only one occasion where we get the output 1??

please explain it.
-Regards
The question asks for a circuit which is given a sequence of bits, one in each round, and is supposed to output $1$ each time that the last $4$ bits form the subsequence $1101$; otherwise $0$ should be output. For example, if the input is $110110101$ then the output should be $000100100$. Naturally, the circuit will have to retain some memory.