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Problem 677


Problem 677


Coloured Graphs

Let g(n) be the number of undirected graphs with n nodes satisfying the following properties:

  • The graph is connected and has no cycles or multiple edges.
  • Each node is either red, blue, or yellow.
  • A red node may have no more than 4 edges connected to it.
  • A blue or yellow node may have no more than 3 edges connected to it.
  • An edge may not directly connect a yellow node to a yellow node.

For example, g(2)=5, g(3)=15, and g(4)=57.
You are also given that g(10)=710249 and g(100)919747298(mod1 000 000 007).

Find g(10 000)mod1 000 000 007.


图染色

g(n)为有n个结点并满足以下性质的无向图总数:

  • 该图是连通图、无环、无重边。
  • 每个结点被染上红色、蓝色或黄色之一。
  • 每个红色结点至多与4条边相连。
  • 每个蓝色或黄色结点至多与3条边相连。
  • 黄色结点之间不能直接相连。

例如,g(2)=5g(3)=15g(4)=57
还已知g(10)=710249g(100)919747298(mod1 000 000 007)

g(10 000)mod1 000 000 007


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