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

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A159353 a(n) = the smallest positive integer such that a(n) *(2^n -2) is a multiple of n. 5
 1, 1, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 7, 5, 8, 1, 9, 1, 10, 7, 11, 1, 12, 5, 13, 9, 2, 1, 15, 1, 16, 11, 17, 35, 18, 1, 19, 13, 20, 1, 21, 1, 22, 3, 23, 1, 24, 7, 25, 17, 26, 1, 27, 55, 28, 19, 29, 1, 30, 1, 31, 21, 32, 13, 33, 1, 34, 23, 5, 1, 36, 1, 37, 25, 38, 77, 39, 1, 40, 27, 41, 1, 42 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS This is not the same sequence as sequence A032742, where A032742(n) = the largest proper divisor of n. See A146077 for numbers n such that the sequences A032742 and A159353 differ. LINKS Michael De Vlieger, Table of n, a(n) for n = 1..10000 FORMULA a(n) = Denominator((2^n - 2)/n). - Juri-Stepan Gerasimov, Sep 09 2014 MATHEMATICA Array[Block[{k = 1}, While[! Divisible[k (2^# - 2), #], k++]; k] &, 84] (* Michael De Vlieger, Oct 30 2017 *) PROG (MAGMA) [Denominator((2^n-2)/n): n in [1..84]]; // Juri-Stepan Gerasimov, Sep 09 2014 (PARI) a(n)=my(k=1); while((2^n-2)*k%n != 0, k++); return(k) \\ Edward Jiang, Sep 09 2014 (PARI) a(n)=denominator(lift(Mod(2, n)^n-2)/n) \\ Charles R Greathouse IV, Sep 11 2014 CROSSREFS Cf. A000918, A146077. Sequence in context: A326139 A325641 A325563 * A032742 A060654 A291329 Adjacent sequences:  A159350 A159351 A159352 * A159354 A159355 A159356 KEYWORD nonn AUTHOR Leroy Quet, Apr 11 2009 EXTENSIONS Extended by Ray Chandler, Apr 11 2009 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.

Last modified November 30 05:31 EST 2020. Contains 338781 sequences. (Running on oeis4.)