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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 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 August 3 11:52 EDT 2020. Contains 336198 sequences. (Running on oeis4.)