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A216949 Expansion of g.f. (1-6*x+7*x^2)/(1-7*x+11*x^2-x^3). 1
1, 1, 3, 11, 45, 197, 895, 4143, 19353, 90793, 426811, 2008307, 9454021, 44513581, 209609143, 987068631, 4648293425, 21889908177, 103085198195, 485455690843, 2286142563933, 10766070546453, 50700381312751, 238762035742207, 1124396126301641, 5295090872259961 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Eric Marberg, Crossings and nestings in colored set partitions, arXiv preprint arXiv:1203.5738 [math.CO], 2012-2013.
Lily Yen, Arc-coloured permutations, PSAC 2013, Paris, France, June 24-28, Proc. DMTCS (2013) 743-754.
Lily Yen, Crossings and Nestings for Arc-Coloured Permutations and Automation, Electronic Journal of Combinatorics, 22(1) (2015), #P1.14.
MATHEMATICA
CoefficientList[Series[(1 - 6 x + 7 x^2)/(1 - 7 x + 11 x^2 - x^3), {x, 0, 30}], x] (* Vincenzo Librandi, Mar 11 2013 *)
CROSSREFS
Sequence in context: A217887 A151129 A151130 * A074532 A049186 A049160
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Sep 22 2012
STATUS
approved

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Last modified April 22 12:55 EDT 2024. Contains 371900 sequences. (Running on oeis4.)