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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A161789 a(n) is the largest integer k such that 2^k - 1 divides n. 3
 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 1, 3, 4, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 2, 3, 1, 4, 5, 1, 2, 1, 3, 2, 1, 1, 2, 1, 1, 3, 1, 1, 4, 1, 1, 2, 3, 1, 2, 1, 1, 2, 1, 3, 2, 1, 1, 4, 1, 5, 6, 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 4, 1, 3, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 4, 3, 1, 5, 1, 1, 2, 1, 3, 2, 1, 1, 2, 1, 1, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A161788(n) = 2^a(n) - 1. a(A161790(n)) = 1. Conjecture: gcd(n, m) = a(2^n + 2^m - 2) for n > 0 and m > 0. - Velin Yanev, Aug 24 2017 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 MAPLE A161789 := proc(n) for k from ilog2(n+1) to 0 by -1 do if n mod (2^k-1) = 0 then RETURN(k); fi; od: end: seq(A161789(n), n=1..120) ; # R. J. Mathar, Jun 27 2009 # Alternative: N:= 200: # for a(1)..a(N) V:= Vector(N, 1): for k from 2 to ilog2(N) do t:= 2^k-1; V[[seq(i, i=t..N, t)]]:= k od: convert(V, list); # Robert Israel, May 12 2020 MATHEMATICA kn[n_]:=Module[{k=Floor[Log[2, n]]+1}, While[!Divisible[n, 2^k-1], k--]; k]; Array[kn, 110] (* Harvey P. Dale, Mar 26 2012 *) PROG (PARI) a(n)=forstep(k=logint(n+1, 2), 1, -1, if(n%(2^k-1)==0, return(k))) \\ Charles R Greathouse IV, Aug 25 2017 CROSSREFS Cf. A000225, A161788, A161790. Sequence in context: A152650 A184219 A180262 * A109671 A141289 A368878 Adjacent sequences: A161786 A161787 A161788 * A161790 A161791 A161792 KEYWORD nonn,easy AUTHOR Leroy Quet, Jun 19 2009 EXTENSIONS Extended by R. J. Mathar, Jun 27 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 15 19:07 EDT 2024. Contains 375173 sequences. (Running on oeis4.)