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 A122132 Squarefree numbers multiplied by binary powers. 15
 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 80, 82, 83, 84, 85 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS These numbers are called "oddly squarefree" in Banks and Luca. - Michel Marcus, Mar 14 2016 The asymptotic density of this sequence is 8/Pi^2 (A217739). - Amiram Eldar, Sep 21 2020 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 William D. Banks and Florian Luca, Roughly squarefree values of the Euler and Carmichael functions, Acta Arithmetica, Vol. 120, No. 3 (2005), pp. 211-230. FORMULA a(n) = A007947(a(n)) * A006519(a(n)) / (2 - a(n) mod 2); A007947(a(n)) = A000265(a(n)) * (2 - a(n) mod 2). A008966(A000265(a(n))) = 1. - Reinhard Zumkeller, Jan 24 2012 A010052(A008477(a(n))) = 1. - Reinhard Zumkeller, Feb 17 2012 MATHEMATICA Select[Range@ 85, SquareFreeQ[#/2^IntegerExponent[#, 2]] &] (* Michael De Vlieger, Mar 15 2020 *) PROG (Haskell) a122132 n = a122132_list !! (n-1) a122132_list = filter ((== 1) . a008966 . a000265) [1..] -- Reinhard Zumkeller, Jan 24 2012 (PARI) is(n)=issquarefree(n>>valuation(n, 2)); \\ Charles R Greathouse IV, Sep 02 2015 CROSSREFS Subsequences: A000079, A005117, A007283, A051916, A056911, A029747. Complement: A038838. Cf. A217739. Sequence in context: A168183 A043094 A023803 * A325389 A020662 A306202 Adjacent sequences:  A122129 A122130 A122131 * A122133 A122134 A122135 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Aug 21 2006 STATUS approved

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Last modified April 11 09:24 EDT 2021. Contains 342886 sequences. (Running on oeis4.)