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A336654 Numbers k such that lambda(k) is squarefree, where lambda is the Carmichael lambda function (A002322). 3
1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 14, 18, 21, 22, 23, 24, 28, 31, 33, 36, 42, 43, 44, 46, 47, 49, 56, 59, 62, 63, 66, 67, 69, 71, 72, 77, 79, 83, 84, 86, 88, 92, 93, 94, 98, 99, 103, 107, 118, 121, 124, 126, 129, 131, 132, 134, 138, 139, 141, 142, 147, 154, 158, 161 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

Imre Kátai, Square-free values of the Carmichael function, Mathematica Pannonica, Vol. 16, No. 2 (2005), pp. 199-203.

Francesco Pappalardi, Filip Saidak and Igor E. Shparlinski, Square-free values of the Carmichael function, Journal of Number Theory, Vol. 103, No. 1 (2003), pp. 122-131.

FORMULA

The number of terms not exceeding x is (k + o(1)) * x/(log(x)^(1-a)), where a = 0.373955... is Artin's constant (A005596), and k = 0.80328... is another constant (Pappalardi et al., 2003).

EXAMPLE

6 is a term since lambda(6) = 2 is squarefree.

MATHEMATICA

Select[Range[160], SquareFreeQ[CarmichaelLambda[#]] &]

CROSSREFS

Cf. A002322, A005117, A005596, A049149, A336655, A336656.

Sequence in context: A200381 A050118 A081754 * A004436 A028237 A194463

Adjacent sequences:  A336651 A336652 A336653 * A336655 A336656 A336657

KEYWORD

nonn

AUTHOR

Amiram Eldar, Jul 28 2020

STATUS

approved

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Last modified October 4 01:04 EDT 2022. Contains 357237 sequences. (Running on oeis4.)