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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A256336 Number of Largest Chain Ladder Family (LCLF) matchings on n edges. 0
1, 3, 14, 81, 521, 3554, 25172, 183129, 1359863, 10264359, 78521474, 607449380, 4744167924, 37355679904, 296232263792, 2363773540473, 18965408058723, 152910824717297, 1238260516988018, 10066874219853977, 82134185988563049, 672294915226393926, 5519252917557226452 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The Largest Chain Ladder Family (LCLF) of matchings is the largest family of matchings formed by repeated edge inflations by ladders and vertex insertions into a chain of any length.

REFERENCES

A. Jefferson, The Substitution Decomposition of Matchings and RNA Secondary Structures, Ph. D. Dissertation, Univ. of Florida, Math., 2015.

LINKS

Table of n, a(n) for n=1..23.

FORMULA

G.f. f satisfies 2x^3f^6-2x^2f^5+4x^2f^4-3xf^3+2xf^2+f-1=0.

EXAMPLE

a(3)=14 because of the 15 matchings on 3 edges, only one does not lie in the Largest Chain Ladder Family. In canonical sequence form, the missing matching is given by 123123.

MAPLE

f := RootOf(2*x^3*_Z^6-2*x^2*_Z^5+4*x^2*_Z^4-3*x*_Z^3+2*x*_Z^2+_Z-1, 1);

series(f, x=0, 30);

CROSSREFS

Sequence in context: A000264 A009053 A202474 * A256338 A256331 A292875

Adjacent sequences:  A256333 A256334 A256335 * A256337 A256338 A256339

KEYWORD

nonn

AUTHOR

Aziza Jefferson, Mar 25 2015

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 April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)