OFFSET
1,3
EXAMPLE
Triangle of normal Lyndon sequences begins:
1,
12,
112,122,123,132,
1112,1122,1123,1132,1213,1222,1223,1232,1233,1234,1243,1322,1323,1324,1332,1342,1423,1432.
MATHEMATICA
LyndonQ[q_]:=Array[OrderedQ[{q, RotateRight[q, #]}]&, Length[q]-1, 1, And]&&Array[RotateRight[q, #]&, Length[q], 1, UnsameQ];
normseqs[n_]:=Union@@Permutations/@Function[s, Array[Count[s, y_/; y<=#]+1&, n]]/@Subsets[Range[n-1]+1];
Table[Select[normseqs[n], LyndonQ], {n, 5}]
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Gus Wiseman, Dec 22 2017
STATUS
approved