yaworsw/euler-manager

---
:id: 351
:name: Hexagonal orchards
:url: https://projecteuler.net/problem=351
:content: "A _hexagonal orchard_ of order <var>n</var> is a triangular lattice made
  up of points within a regular hexagon with side <var>n</var>. The following is an
  example of a hexagonal orchard of order 5:\n\n ![p351_hexorchard.png]({{ images_dir
  }}/p351_hexorchard.png)  \n\nHighlighted in green are the points which are hidden
  from the center by a point closer to it. It can be seen that for a hexagonal orchard
  of order 5, 30 points are hidden from the center.\n\nLet H(<var>n</var>) be the
  number of points hidden from the center in a hexagonal orchard of order <var>n</var>.\n\nH(5)
  = 30. H(10) = 138. H(1 000) = 1177848.\n\nFind H(100 000 000).\n\n"