To find first N prime numbers in python

Question

I am new to the programming world. I was just writing this code in python to generate N prime numbers. User should input the value for N which is the total number of prime n

Answer 1

def isPrime(y):
  i=2
  while i < y:
    if y%i == 0 :
      return 0
      exit()
    i=i+1
  return 1

x= raw_input('Enter the position 1st,2nd,..nth prime number you are looking for?: ')
z=int(x)
# for l in range(2,z)
count = 1
n = 2
while count <= z:
  if isPrime(n) == 1:
    if count == z:
      print n
    count +=1
  n=n+1

Answer 2

n=int(input("Enter the number:: "))

for i in range(2,n):
    p=i
    k=0
    for j in range(2,p-1):
        if(p%j==0):
            k=k+1
    if(k==0):
        print(p)

Answer 3

count = -1
n = int(raw_input("how many primes you want starting from 2 "))
primes=[[]]*n
for p in range(2, n**2):
    for i in range(2, p):
        if p % i == 0:
            break
    else:
        count +=1
        primes[count]= p
        if count == n-1:
            break

print (primes)
print 'Done'

Answer 4

What you want is something like this:

x = int(input("Enter the number:"))
count = 0
num = 2
while count < x:
     if isnumprime(x):
        print(x)
        count += 1
     num += 1

I'll leave it up to you to implement isnumprime() ;) Hint: You only need to test division with all previously found prime numbers.

Answer 5

Until we have N primes, take natural numbers one by one, check whether any of the so-far-collected-primes divide it.

If none does, "yay", we have a new prime...

that's it.

>>> def generate_n_primes(N):
...     primes  = []
...     chkthis = 2
...     while len(primes) < N:
...         ptest    = [chkthis for i in primes if chkthis%i == 0]
...         primes  += [] if ptest else [chkthis]
...         chkthis += 1
...     return primes
...
>>> print generate_n_primes(15)
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]

Answer 6

Try using while loop to check the count, that is easy. Find the code snippet below :

i=1
count = 0;
x = int(input("Enter the number:\n"))
while (count < x):
c=0
for j in range (1, (i+1), 1):
    a = i%j
    if (a==0):
        c = c+1

if (c==2):
      print (i)
      count = count+1
i=i+1