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

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100617 There are n people in a room. First half (i.e. [n/2]) of them leave, then 1/3 (i.e. floor of 1/3) of those remaining leave, then 1/4, then 1/5, etc.; sequence gives number who remain at the end. 2
1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

V. Brun, Un proc\'{e}d\'{e} qui ressemble au crible d'Eratosthene, Analele Stiintifice Univ. "Al. I. Cuza", Iasi, Romania, Sect. Ia Matematica, 1965, vol. 11B, pp. 47-53.

LINKS

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

FORMULA

a(n) = k for Fl(k) <= n < Fl(k+1), where Fl(i) = A000960(i).

EXAMPLE

7 -> 7 - [7/2] = 7 - 3 = 4 -> 4 - [4/3] = 4 - 1 = 3 -> 3 - [3/4] = 3 - 0 = 3, which is now fixed, so a(7) = 3.

MAPLE

f:=proc(n) local i, j, k; k:=n; for i from 2 to 10000 do j := floor(k/i); if j < 1 then break; fi; k := k-j; od; k; end;

MATHEMATICA

a[n_] := (k = 2; FixedPoint[# - Floor[# / k++]&, n]); Table[a[n], {n, 1, 96}] (* Jean-Fran├žois Alcover, Nov 15 2011 *)

PROG

(Haskell)

a100617 = f 2 where

   f k x = if x' == 0 then x else f (k + 1) (x - x') where x' = div x k

-- Reinhard Zumkeller, Jul 01 2013, Sep 15 2011

CROSSREFS

Cf. A000960, A100618.

Sequence in context: A000194 A168255 A097429 * A076471 A165116 A111656

Adjacent sequences:  A100614 A100615 A100616 * A100618 A100619 A100620

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Dec 03 2004

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified November 23 00:45 EST 2014. Contains 249836 sequences.