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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A141349 Size of the reduced Groebner basis of the ideal < x*y(1)^vj(1)*...*y(n-2)^vj(n-2) - z(j) : j=1,2,...,m >, where vj is the j-th extreme n-breakable vector, m=A141348(n), w.r.t. the degree of x and graded reverse lexicographic ordering of the variables y(1), ..., y(n-2), z(1), ..., z(m). 2
1, 3, 9, 43, 125, 1117, 8227 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Table of n, a(n) for n=3..9.

Max A. Alekseyev and Pavel A. Pevzner, "Multi-Break Rearrangements and Chromosomal Evolution". Theoretical Computer Science 395(2-3) (2008), pp. 193-202.

EXAMPLE

The Groebner basis corresponding to the set of extreme 4-breakable vectors { (1,0), (0,2) } is { y(2)^2*z(1) - y(1)*z(1), x*y(1) - z1, x*y(2)^2 - z(1) }, implying that a(4)=3.

CROSSREFS

Cf. A141347, A141348.

Sequence in context: A081681 A281940 A141774 * A018427 A275781 A199140

Adjacent sequences:  A141346 A141347 A141348 * A141350 A141351 A141352

KEYWORD

nonn,hard,more

AUTHOR

Max Alekseyev, Jun 27 2008

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 August 20 18:56 EDT 2019. Contains 326154 sequences. (Running on oeis4.)