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 A130977 G.f.: 5/(2 + 3*sqrt(1-20*x)). 6
 1, 6, 66, 876, 12786, 197796, 3183156, 52718616, 892401426, 15368638836, 268388185596, 4741271556456, 84573471344916, 1521119577791976, 27554494253636136, 502257203287150896, 9205363627419463506 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of walks of length 2n on the 6-regular tree beginning and ending at some fixed vertex. Hankel transform is A135349. - Philippe Deléham, Feb 25 2009 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA a(n) = Sum_{k=0..n} A039599(n,k)*5^(n-k). - Philippe Deléham, Aug 25 2007 From Gary W. Adamson, Jul 22 2011: (Start) a(n) = upper left term in M^n, M = an infinite square production matrix as follows:   6, 6, 0, 0, 0, 0, ...   5, 5, 5, 0, 0, 0, ...   5, 5, 5, 5, 0, 0, ...   5, 5, 5, 5, 5, 0, ...   5, 5, 5, 5, 5, 5, ...   ... (End) D-finite with recurrence: n*a(n) = 2*(28*n-15)*a(n-1) - 360*(2*n-3)*a(n-2). - Vaclav Kotesovec, Oct 20 2012 a(n) ~ 3*2^(2*n-3)*5^(n+1)/(sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Oct 20 2012 MATHEMATICA CoefficientList[Series[5/(2+3*Sqrt[1-20*x]), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *) CROSSREFS Column k=6 of A183135. Sequence in context: A004355 A282046 A124862 * A191096 A151832 A133306 Adjacent sequences:  A130974 A130975 A130976 * A130978 A130979 A130980 KEYWORD nonn AUTHOR Philippe Deléham, Aug 23 2007 EXTENSIONS More terms from Olivier Gérard, Sep 22 2007 STATUS approved

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Last modified September 28 04:24 EDT 2021. Contains 347698 sequences. (Running on oeis4.)