def is_truncated_prime(n):
str_n = str(n)
for i, _ in enumerate(str_n):
try:
if not (is_prime(int(str_n[i:])) and is_prime(int(str_n[:i]))):
return False
except ValueError:
continue
return True
def solve():
prime_count = 3
side_length = 2
count = 9
while prime_count / (2 * side_length + 1) > 0.10:
side_length += 2
for i in range(3):
count += side_length
if is_prime(count):
prime_count += 1
count += side_length
return side_length + 1
def solve():
# Only test for 7 digit pandigitals, as all 8/9-digit pandigitals are divisible by 3
for pandigital in sorted(pandigital_list(7), reverse=True):
pandigital = int(pandigital)
if is_prime(pandigital):
return pandigital
