Python is_prime

Question

Assume the availability of a function is_prime. Assume a variable n has been associated with positive integer. Write the statements needed to compute the sum of the first n prime numbers. The sum should be associated with the variable total.

Note: is_prime takes an integer as a parameter and returns True if and only if that integer is prime.

So far I have:

i=2
count=0
total=0
while (count<n):
    if(is_prime(i)):
        total+=1
        count+=1
    i+=1

Where am I missing the problem.

Thanks for the edit, was in process of editing when you did. — Randy, Apr 09 '16 at 17:39
you dont have a function and its not returning ... plus you should probably be adding `i` `total += i` — Joran Beasley, Apr 09 '16 at 17:43
Possible duplicate of [isPrime Function for Python Language](http://stackoverflow.com/questions/15285534/isprime-function-for-python-language) — Anil_M, Apr 09 '16 at 17:45
@Anil_M i think he has an `is_prime` method provided to him ... (he isnt trying to write is_prime) — Joran Beasley, Apr 09 '16 at 17:46

score 1 · Answer 1 · answered Apr 09 '16 at 17:47

to fix your existing ... just add i to total

i=2
count=0
total=0
while (count<n):
    if(is_prime(i)):
        total+=i
        count+=1
    i+=1
print total

you could make it much better by making a generator to yield primes forever

def primes():
   for i in itertools.count(1):
       if is_prime(i):
          yield i

then you could make n_primes that yields the first n primes

def n_primes(n):
    return [prime for prime,_ in zip(primes(),range(n))]

then lastly you just sum it

print sum(n_primes(N))

Thank Joran, I knew I was overlooking something so simple. – Randy Apr 09 '16 at 17:55 — Randy, Apr 09 '16 at 17:55

Python is_prime

1 Answers1