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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

Table of n, a(n) for n=1..8.

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

Cf. A014606, A025035.

Sequence in context: A276015 A210823 A258336 * A160307 A003030 A276016

Adjacent sequences:  A211307 A211308 A211309 * A211311 A211312 A211313

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 08 2012

STATUS

approved

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Last modified February 16 09:23 EST 2019. Contains 320161 sequences. (Running on oeis4.)