i got this.
the sequence is periodic modulo any positive integer m.
bt i dont know this modulo concept yet. So i should wait till then or there is sme another way for doing it?
i don't know of any other method..
also, most of the question related to such topics are solved using modular algebra,
this is a tribonacci sequence. then we have the fibonacci sequence, etc.
you can read some stuff on their properties on wikipedia..