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A329131 Numbers whose prime signature is a Lyndon word. 21
2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 18, 19, 23, 25, 27, 29, 31, 32, 37, 41, 43, 47, 49, 50, 53, 54, 59, 61, 64, 67, 71, 73, 75, 79, 81, 83, 89, 97, 98, 101, 103, 107, 108, 109, 113, 121, 125, 127, 128, 131, 137, 139, 147, 149, 150, 151, 157, 162, 163, 167 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

First differs from A133811 in having 50.

A Lyndon word is a finite sequence that is lexicographically strictly less than all of its cyclic rotations.

A number's prime signature is the sequence of positive exponents in its prime factorization.

LINKS

Table of n, a(n) for n=1..61.

FORMULA

Intersection of A329138 and A329139.

EXAMPLE

The prime signature of 30870 is (1,2,1,3), which is a Lyndon word, so 30870 is in the sequence.

The sequence of terms together with their prime indices begins:

    2: {1}

    3: {2}

    4: {1,1}

    5: {3}

    7: {4}

    8: {1,1,1}

    9: {2,2}

   11: {5}

   13: {6}

   16: {1,1,1,1}

   17: {7}

   18: {1,2,2}

   19: {8}

   23: {9}

   25: {3,3}

   27: {2,2,2}

   29: {10}

   31: {11}

   32: {1,1,1,1,1}

MATHEMATICA

lynQ[q_]:=Array[Union[{q, RotateRight[q, #]}]=={q, RotateRight[q, #]}&, Length[q]-1, 1, And];

Select[Range[2, 100], lynQ[Last/@FactorInteger[#]]&]

CROSSREFS

Numbers whose reversed binary expansion is Lyndon are A328596.

Numbers whose prime signature is a necklace are A329138.

Numbers whose prime signature is aperiodic are A329139.

Lyndon compositions are A059966.

Prime signature is A124010.

Cf. A000031, A000740, A000961, A001037, A025487, A027375, A097318, A112798, A118914, A304678, A318731, A329140, A329142.

Sequence in context: A046684 A082377 A166401 * A334965 A133811 A316525

Adjacent sequences:  A329128 A329129 A329130 * A329132 A329133 A329134

KEYWORD

nonn

AUTHOR

Gus Wiseman, Nov 06 2019

STATUS

approved

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Last modified December 7 20:19 EST 2021. Contains 349588 sequences. (Running on oeis4.)