For knowing what N is before having calcualted up to it, the only option is to have it stored.I am not sure about magical, but here is a practical way. Let's say you need to compute Fibonacci sequence from F(n) to F(m). If you have p cores, split the interval (n;m) into p equal segments.
Wich part of "Storage does not count" did you miss?
Because surpisingly, we do not know the value of a calculation before having done it.