python - Backtracking to generate all numbers within constraint -

i trying create function generates numbers can formed through combination of primes satisfy constraint of being within 99% of number , less or equal number. primes [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43] , exponents [39, 19, 9 , 6, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1]

the code have uses 1 of each prime , stops, 2^1*3^1*5^1*...*17^1 or something, doesn't increment exponents. not sure wrong here, don't know problem is. here code

def rec(start):     global freqa     global     global exp     if start >=length:return true     print a," ",freqa     if a>= int(0.99*curt):         in xrange(length):             exp[i]=exponents[i]-freqa[i]         rec1(0)      in xrange(exponents[start]):          freqa[start]+=1         a*=primes[start]         if a<=curt ,  rec(start+1): return true         freqa[start]-=1         a/=primes[start] return false 

line

exp[i]=exponents[i]-freqa[i] 

not in loop

just in case: 17! = 355 687 428 096 000