﻿# -*- coding: utf-8 -*-
# ProjectEuler/src/python/problem128.py
#
# Hexagonal tile differences
# ==========================
# Published on Friday, 29th September 2006, 06:00 pm
#
# A hexagonal tile with number 1 is surrounded by a ring of six hexagonal
# tiles, starting at "12 o'clock" and numbering the tiles 2 to 7 in an anti-
# clockwise direction. New rings are added in the same fashion, with the next
# rings being numbered 8 to 19, 20 to 37, 38 to 61, and so on. The diagram
# below shows the first three rings.    By finding the difference between tile
# n and each its six neighbours we shall define PD(n) to be the number of those
# differences which are prime. For example, working clockwise around tile 8 the
# differences are 12, 29, 11, 6, 1, and 13. So PD(8) = 3. In the same way, the
# differences around tile 17 are 1, 17, 16, 1, 11, and 10, hence PD(17) = 2. It
# can be shown that the maximum value of PD(n) is 3. If all of the tiles for
# which PD(n) = 3 are listed in ascending order to form a sequence, the 10th
# tile would be 271. Find the 2000th tile in this sequence.

import projecteuler as pe

def main():
    pass

if __name__ == "__main__":
    main()
