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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056920 Denominators of continued fraction for left factorial. 3
1, 1, 0, -1, -1, 1, 4, 1, -15, -19, 56, 151, -185, -1091, 204, 7841, 6209, -56519, -112400, 396271, 1520271, -2442439, -19165420, 7701409, 237686449, 145269541, -2944654296, -4833158329, 36392001815, 104056218421, -441823808804, -2002667085119, 5066513855745, 37109187217649 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..895

FORMULA

a(0)=1, a(1)=1, a(n) = a(n-1) - floor(n/2)*a(n-2).

MAPLE

a:= proc(n) option remember;

   if n<2 then 1

   else a(n-1) - floor(n/2)*a(n-2)

   fi; end:

seq(a(n), n=0..40); # G. C. Greubel, Dec 05 2019

MATHEMATICA

a[n_]:= a[n]= If[n<2, 1, a[n-1] -Floor[n/2]*a[n-2]]; Table[a[n], {n, 0, 40}] (* G. C. Greubel, Dec 05 2019 *)

PROG

(PARI) a(n) = if(n<2, n, a(n-1) - (n\2)*a(n-2) ); \\ G. C. Greubel, Dec 05 2019

(MAGMA)

function a(n)

  if n lt 2 then return 1;

  else return a(n-1) - Floor(n/2)*a(n-2);

  end if; return a; end function;

[a(n): n in [0..40]]; // G. C. Greubel, Dec 05 2019

(Sage)

@CachedFunction

def a(n):

    if (n<2): return 1

    else: return a(n-1) - floor(n/2)*a(n-2)

[a(n) for n in (0..40)] # G. C. Greubel, Dec 05 2019

(GAP)

a:= function(n)

    if n<2 then return 1;

    else return a(n-1) - Int(n/2)*a(n-2);

    fi; end;

List([0..40], n-> a(n) ); # G. C. Greubel, Dec 05 2019

CROSSREFS

Sequence in context: A159764 A124029 A207823 * A123382 A197653 A146160

Adjacent sequences:  A056917 A056918 A056919 * A056921 A056922 A056923

KEYWORD

sign,frac,easy

AUTHOR

Aleksandar Petojevic (apetoje(AT)ptt.yu), Sep 05 2000

EXTENSIONS

More terms from James A. Sellers, Sep 06 2000

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 February 28 06:55 EST 2020. Contains 332321 sequences. (Running on oeis4.)