### # Prime permutations # Problem 49 # # The arithmetic sequence, 1487, 4817, 8147, in which each of the terms increases by 3330, is unusual in two ways: (i) each of the three terms are prime, and, (ii) each of the 4-digit numbers are permutations of one another. # There are no arithmetic sequences made up of three 1-, 2-, or 3-digit primes, exhibiting this property, but there is one other 4-digit increasing sequence. # What 12-digit number do you form by concatenating the three terms in this sequence? ### import math def is_prime(n): if n % 2 == 0 or n % 3 == 0 or n % 5 == 0: return False for d in range(6, math.floor(math.sqrt(n)) + 1, 6): if n % (d - 1) == 0 or n % (d + 1) == 0: return False return True for n1 in range(1001, 10000, 2): for n2 in range(n1 + 2, 10000, 2): n3 = n2 + (n2 - n1) s = sorted(str(n1)) if s != sorted(str(n2)) or s != sorted(str(n3)): continue if is_prime(n1) and is_prime(n2) and is_prime(n3): print(n1, n2, n3)