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!)
A211310 a(n) = number |fdw(P,(n))| of entangled P-words with s=3. 0
1, 18, 1566, 354456, 163932120, 134973740880, 180430456454640, 366311352681348480 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
See Jenca and Sarkoci for the precise definition.
LINKS
Gejza Jenca and Peter Sarkoci, Linear extensions and order-preserving poset partitions, arXiv preprint arXiv:1112.5782, 2011
FORMULA
From Peter Bala, Sep 05 2012: (Start)
Conjectural e.g.f.: 2 - 1/A(x), where A(x) = sum {n = 0..inf} (3*n)!/6^n*x^n/n! is the e.g.f. for A014606 (also the o.g.f. for A025035).
If true, this leads to the recurrence equation: a(n) = (3*n)!/6^n - sum {k = 1..n-1} (3*k)!/6^k*binomial(n,k)*a(n-k) with a(1) = 1.
(End)
CROSSREFS
Sequence in context: A276015 A210823 A258336 * A160307 A003030 A276016
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 08 2012
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 29 05:48 EDT 2024. Contains 371265 sequences. (Running on oeis4.)