The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A122132 Squarefree numbers multiplied by binary powers. 23
 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: A043094 A023803 A353511 * A347248 A347243 A325389 Adjacent sequences: A122129 A122130 A122131 * A122133 A122134 A122135 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Aug 21 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 1 14:21 EST 2022. Contains 358468 sequences. (Running on oeis4.)