login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A122132 Squarefree numbers multiplied by binary powers. 8
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

a(n) = A007947(a(n)) * A006519(a(n)) / (2 - a(n) mod 2);

A007947(a(n)) = A000265(a(n)) * (2 - a(n) mod 2).

A010052(A008477(a(n))) = 1. - Reinhard Zumkeller, Feb 17 2012

These numbers are called "oddly squarefree" in Banks and Luca. - Michel Marcus, Mar 14 2016

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

William D. Banks, Florian Luca, Roughly squarefree values of the Euler and Carmichael functions, Acta Arithmetica 120(2005), 211-230.

FORMULA

A008966(A000265(a(n))) = 1. - Reinhard Zumkeller, Jan 24 2012

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.

Sequence in context: A168183 A043094 A023803 * A325389 A020662 A306202

Adjacent sequences:  A122129 A122130 A122131 * A122133 A122134 A122135

KEYWORD

nonn

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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 26 14:08 EST 2020. Contains 331280 sequences. (Running on oeis4.)