login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A082010 a(n) = n/2 if n is even, otherwise floor(8*n/5)+1. 3

%I

%S 0,2,1,5,2,9,3,12,4,15,5,18,6,21,7,25,8,28,9,31,10,34,11,37,12,41,13,

%T 44,14,47,15,50,16,53,17,57,18,60,19,63,20,66,21,69,22,73,23,76,24,79,

%U 25,82,26,85,27,89,28,92,29,95,30,98,31,101,32,105,33,108,34,111,35,114,36,117

%N a(n) = n/2 if n is even, otherwise floor(8*n/5)+1.

%C See A152199 for the orbit of 7 under this map (which includes the orbit of 3, 5, 6, 7, 9, ... as well). - _M. F. Hasler_, Jun 12 2012

%C This is the 8/5 map, a particular case of the m/n sequence mentioned by _Yasutoshi Kohmoto_ on the SeqFan list (cf. link), which also includes the Collatz map A014682 (for m/n = 3/2). - _M. F. Hasler_, Jun 12 2012

%H Yasutoshi Kohmoto, <a href="http://list.seqfan.eu/pipermail/seqfan/2009-September/002431.html">8/5 Sequence</a>, SeqFan list, Sep 30 2009

%H OEIS wiki, <a href="/wiki/M/n_sequences">m/n sequences</a>, _M. F. Hasler_, Jun 12 2012

%H <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1).

%F a(n) = +a(n-2) +a(n-10) -a(n-12). G.f.: x*(1+x+x^2)*(x^8+2*x^6-x^5+2*x^4+2*x^2-x+2) / ( (1+x+x^2+x^3+x^4)*(x^4-x^3+x^2-x+1)*(x-1)^2*(1+x)^2 ). - _R. J. Mathar_, Feb 20 2011

%t Table[If[EvenQ[n],n/2,Floor[(8n)/5+1]],{n,0,80}] (* or *) LinearRecurrence[ {0,1,0,0,0,0,0,0,0,1,0,-1},{0,2,1,5,2,9,3,12,4,15,5,18},80] (* _Harvey P. Dale_, Dec 18 2012 *)

%o (PARI) A082010(x)=if(bittest(x,0),8*x\5+1,x\2) \\ _M. F. Hasler_, Jun 12 2012

%K nonn

%O 0,2

%A _N. J. A. Sloane_, Oct 06 2009, suggested by postings to the Sequence Fans Mailing List by _Yasutoshi Kohmoto_ and _Franklin T. Adams-Watters_, Sep 30 2009

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 April 26 09:52 EDT 2019. Contains 322472 sequences. (Running on oeis4.)