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PROJECT EULER · #0763

Amoebas in a 3D Grid

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Consider a three dimensional grid of cubes. An amoeba in cube (x,y,z) can divide itself into three amoebas to occupy the cubes (x+1,y,z), (x,y+1,z) and (x,y,z+1), provided these cubes are empty.

Originally there is only one amoeba in the cube (0,0,0). After N divisions there will be 2N+1 amoebas arranged in the grid. An arrangement may be reached in several different ways but it is only counted once. Let D(N) be the number of different possible arrangements after N divisions.

For example, D(2)=3, D(10)=44499, D(20)=9204559704 and the last nine digits of D(100) are 780166455.

Find D(10000), enter the last nine digits as your answer.

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