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PROJECT EULER · #0351

Hexagonal Orchards

Statement only · SolvedOriginal problem ↗

A hexagonal orchard of order n is a triangular lattice made up of points within a regular hexagon with side n. The following is an example of a hexagonal orchard of order 5:

0351_hexorchard.png

Highlighted 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.

Let H(n) be the number of points hidden from the center in a hexagonal orchard of order n.

H(5)=30. H(10)=138. H(1000)=1177848.

Find H(100000000).

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