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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A113975 Devil's Farey: coefficient expansion of a quadratic over quadratic that has 123 roots and a Farey p[1/2]=1 ( correction). 0
2, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
I call it the devil's Farey because of the 6,6,6 structure. I was trying to get an integer root quadratic over quadratic that had the Farey conditions: p[1/2]=1;p[0]=0;p[1]=0
The function has the characteristic Farey shape: fa[x_] := 1/p[x] /; 0 <= x <= 1/2 fa[x_] := p[x] /; 1/2 < x <= 1.
LINKS
FORMULA
b(n)= coefficient expansion of 1 + 2/x - 6/(1 - x) a(n) = b(n)
MATHEMATICA
a = 1; b = 2; c = 3; d = 3; e = 0; f = -1 p[x_] = FullSimplify[ExpandAll[(x - a)*(x - b)*(x - c)/((x - d)*(x - e)*(x -f))]] a = Abs[ReplacePart[Table[Abs[Coefficient[Series[p[x], {x, 0, 30}], x^n]], {n, -1, 30}], -5, 2]]
CROSSREFS
Cf. A113923.
Sequence in context: A008294 A019694 A233588 * A035585 A239868 A159076
KEYWORD
nonn,uned
AUTHOR
Roger L. Bagula, Jan 31 2006
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 01:22 EDT 2024. Contains 370952 sequences. (Running on oeis4.)