A357810 Number of n-step closed paths on the Cairo pentagonal lattice graph starting from a degree-4 node.
1, 0, 4, 0, 24, 8, 164, 136, 1236, 1704, 10116, 19144, 88616, 205208, 818764, 2155160, 7873440, 22463400, 77954740, 233894600, 788314984, 2440865400, 8095906076, 25569342520, 84107990356, 269034666280
Offset: 0
Examples
For n=2, the a(2) = 4 solutions visit one of the four vertices adjacent to the initial vertex, and then return. For n=5, the a(5) = 8 solutions consist of counterclockwise or clockwise traversals of the circumference of any of the four pentagons that surround the initial vertex.
Links
- Wikipedia, Cairo pentagonal tiling