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 A114300 Number of non-intersecting cycle systems in a particular directed graph. 1
 1, 2, 5, 17, 40, 101, 260, 677, 1768, 4625, 12104, 31685, 82948, 217157, 568520, 1488401, 3896680, 10201637, 26708228, 69923045, 183060904, 479259665, 1254718088, 3284894597, 8599965700, 22515002501, 58945041800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Define a graph with 2n vertices. Vertices 1 through n will be on the top half, vertices n+1 through 2n will be on the bottom half. For 1 <= i < j <=n, create a directed edge from vertex i to vertex j whenever j=i+2. For n+1<=icoeff(series((1-x-x^2+5*x^3-6*x^4-6*x^5+3*x^6)/(1-3*x+3*x^3-x^4), x=0, n+1), x, n); MATHEMATICA CoefficientList[Series[(3x^6-6x^5-6x^4+5x^3-x^2-x+1)/ (-x^4+3x^3-3x+1), {x, 0, 30}], x]  (* Harvey P. Dale, Apr 19 2011 *) CROSSREFS See also A112831 and A112832. Sequence in context: A118727 A183906 A042361 * A099207 A197918 A122566 Adjacent sequences:  A114297 A114298 A114299 * A114301 A114302 A114303 KEYWORD easy,nonn AUTHOR Christopher Hanusa (chanusa(AT)math.binghamton.edu), Nov 21 2005 STATUS approved

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