A376988 Number of polycubes of size n and symmetry class EF.
0, 0, 0, 0, 0, 1, 1, 2, 3, 6, 7, 13, 20, 32, 43, 71, 109, 162, 226, 363, 553, 811
Offset: 1
Links
- John Mason, Counting free polycubes
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
For n=2 there are three possibilities: the two cubes share a face, or only an edge, or only a vertex. For n=3, there are 14 tricubes allowing vertex, edge, and face connections. Two of them have distinct mirror images, so a(3) = 16.
A cube-shaped void can be made by concealing it with 6 cubes, which is the minimal number to do so. So a(1)=6. A dicube-shaped void can be made by concealing it with 10 cubes, which is the minimal number to do so. So a(2)=10.
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