39 lines
779 B
Python
39 lines
779 B
Python
|
#!/usr/bin/env python3
|
||
|
|
|
||
|
|
def getprimes(n):
|
||
|
|
sieve = [True] * n
|
||
|
|
for p in range(3, n, 2):
|
||
|
|
if not sieve[p]:
|
||
|
|
continue
|
||
|
|
for i in range(p**2, n, 2*p):
|
||
|
|
sieve[i] = False
|
||
|
|
return sieve
|
||
|
|
|
||
|
|
def is_prime(n):
|
||
|
|
if n == 2:
|
||
|
|
return True
|
||
|
|
return n % 2 and sieve[n]
|
||
|
|
|
||
|
|
N = 10**8
|
||
|
|
sieve = getprimes(N)
|
||
|
|
primes = [2] + [n for n in range(3, N, 2) if sieve[n]]
|
||
|
|
|
||
|
|
for n in range(2, int(N**0.5)+1):
|
||
|
|
b = n**2
|
||
|
|
if n % 2:
|
||
|
|
b *= 2
|
||
|
|
for i in range(b, N, b):
|
||
|
|
sieve[i] = n
|
||
|
|
|
||
|
|
s = 0
|
||
|
|
|
||
|
|
for p in primes:
|
||
|
|
d = sieve[p+1]
|
||
|
|
k = d + 1
|
||
|
|
while ((p+1) * k**2)/d**2 <= N:
|
||
|
|
if is_prime(((p+1)*k)//d - 1) and is_prime(((p+1)*k**2)//d**2 - 1):
|
||
|
|
s += p + ((p+1)*k)//d - 1 + ((p+1)*k**2)//d**2 - 1
|
||
|
|
k += 1
|
||
|
|
|
||
|
|
print(s)
|