rspd.py

class RSPD(object):
    def __init__(self, base10):
        #if base10 > 210:
        #    raise NotImplemented

        self.values = []
        self.value = str()
        remainder = int()
        self.primes = primes_less_than(base10)

        if len(self.primes) < 4: self.primes = [2,3,5,7]

        while base10 not in self.values or len(self.values) < 4:
            try:
                remainder = base10 % self.primes.pop(0)
            except:
                break
            self.values.insert(0, remainder)

        for value in self.values:
            self.value += str(value)

def primes_less_than(n): aux = {}; return [aux.setdefault(p,p) for p in range(2, n) if 0 not in [p%d for d in aux if p>=d+d]]