■DE群多面体の面数公式(その233)

 七角形への二重節点の付け方は何通りあるだろうか?

[0]()

[1](0)

[2](0,1)(0,2)(0,3)

[3](0,1,2)(0,1,3)(0,1,4)(0,2,4)

・・・・・・・・・・・・・・・・・・

[7](0,1,2,3,4,5,6)

[0]=[7],[1]=[6],[2]=[5],[3]=[4]

18通り

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 八角形への二重節点の付け方は何通りあるだろうか?

[0]()

[1](0)

[2](0,1)(0,2)(0,3)(0,4)

[3](0,1,2)(0,1,3)(0,1,4)(0,2,4)(0,2,5)

[4]0,1,2,3)(0,1,2,4)(0,1,2,5)(0,1,3,4)(0,1,3,5)(0,1,3,6)(0,1,4,5)(0,2,4,6)

・・・・・・・・・・・・・・・・・・

[8](0,1,2,3,4,5,6,7)

[0]=[8],[1]=[7],[2]=[6],[3]=[5]

30通り

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