It can, as
@Dan B pointed out, be accurately represented by the single symbol π, or as
@gom pointed out by the sequence of symbols ln(-1)/i, or in any number of other ways, some involving infinite sequences.
It can never be accurately represented in finite space using a decimal representation - but that's not the same thing.
So:
The first part is incorrect - there are infinite sequences which others will know better than me which add to simple functions of pi. The second part is also incorrect - theoretically it's just itself, the ratio between the idealised diameter and the idealised circumference of an idealised circle. Practically it's approximated by 3.14, or by 3.141592653 - whatever number of decimal places you need for your real-world calculation.