Creating higher order neighbours lists
## [[1]]
## [[1]][[1]]
## [1] 2 3
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## [[1]][[2]]
## [1] 1 3 4
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## [[2]]
## [[2]][[1]]
## [1] 4 5
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## [[2]][[2]]
## [1] 5 8
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## [[3]]
## [[3]][[1]]
## [1] 6 8 9 11 15 16
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## [[3]][[2]]
## [1] 6 7 9 11 12 13 15 16