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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128773 a(n) = denominator of r(n): r(1)=1, r(n+1) = [b(1,n);b(2,n),...,b(n,n)], a continued fraction of rational terms, where {b(k,n)} is the permutation of the first n terms of {r(k)} such that r(n+1) is maximized. 4
1, 1, 1, 2, 4, 100, 100, 405700, 12160319136100, 820172805359644669394378100, 833851539054293743258980868256234722984430395524650100, 4967797610707807275548011269672520283591314213501804232311981072548746611502282121553381887584145907359338100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..15

EXAMPLE

The first 5 terms of {r(k)} are: 1,1,2,5/2,13/4. The continued fraction, whose terms are the permutation of the first 5 terms of {r(k)} which leads to the largest r(6), is [13/4;1,5/2,1,2] = 401/100.

MAPLE

Ltoc := proc(L) numtheory[nthconver](L, nops(L)-1) ; end: r := proc(n) option remember ; local m, rL, rp, L ; if n = 1 then 1; else m := -1 ; rL := [seq(procname(i), i=1..n-1)] ; rp := combinat[permute](rL) ; for L in rp do m := max(m, Ltoc(L)) ; od: m ; fi; end: A128773 := proc(n) denom(r(n)) ; end: for n from 1 do printf("%d, \n", A128773(n)) ; od: # R. J. Mathar, Jul 30 2009

tor:= proc(l) local j; infinity; for j from nops(l) to 1 by -1 do l[j]+1/% od end: sh:= proc(l) local ll, h, s, m; ll:= []; h:= nops(l); s:= 1; m:= h; while s<=h do ll:= [ll[], l[m]]; if m=h then h:= h-1; m:= s else s:= s+1; m:= h fi od; ll end: r:= proc(n) option remember; local j; `if`(n=1, 1, tor(sh(sort([seq(r(j), j=1..n-1)])))) end: a:= n-> denom(r(n)): seq(a(n), n=1..12); # Alois P. Heinz, Aug 04 2009

CROSSREFS

Cf. A128772, A128774, A128775.

Sequence in context: A009379 A092918 A018428 * A101068 A018435 A166094

Adjacent sequences:  A128770 A128771 A128772 * A128774 A128775 A128776

KEYWORD

frac,nonn

AUTHOR

Leroy Quet, Mar 27 2007

EXTENSIONS

3 more terms from R. J. Mathar, Jul 30 2009

a(10)-a(12) from Alois P. Heinz, Aug 04 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 16 10:23 EDT 2019. Contains 327094 sequences. (Running on oeis4.)