# Check whether the given number is Euclid Number or not in Python

PythonServer Side ProgrammingProgramming

Suppose we have a number n. We have to check whether n is Euclid number or not. As we know Euclid numbers are integer which can be represented as

n= Pn+1

where  is product of first n prime numbers.

So, if the input is like n = 211, then the output will be True n can be represented as

211=(2×3×5×7)+1

To solve this, we will follow these steps −

• MAX := 10000
• primes := a new list
• Define a function generate_all_primes() . This will take
• prime := a list of size MAX and fill with True
• x := 2
• while x * x < MAX, do
• if prime[x] is True, then
• for i in range x * 2 to MAX, update in each step by x, do
• prime[i] := False
• x := x + 1
• for x in range 2 to MAX - 1, do
• if prime[x] is true, then
• insert x at the end of primes
• From the main method do the following:
• generate_all_primes()
• mul := 1, i := 0
• while mul < n, do
• mul := mul * primes[i]
• if mul + 1 is same as n, then
• return True
• i := i + 1
• return False

Let us see the following implementation to get better understanding −

## Example Code

Live Demo

MAX = 10000
primes = []

def generate_all_primes():
prime = [True] * MAX

x = 2
while x * x < MAX :
if prime[x] == True:
for i in range(x * 2, MAX, x):
prime[i] = False
x += 1

for x in range(2, MAX):
if prime[x]:
primes.append(x)

def solve(n):
generate_all_primes()
mul = 1
i = 0

while mul < n :
mul = mul * primes[i]
if mul + 1 == n:
return True
i += 1
return False

n = 211
print(solve(n))

## Input

211

## Output

True
Published on 16-Jan-2021 04:52:49