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A130977
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G.f. : 5/(2+3*sqrt(1-20*x)).
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5
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1, 6, 66, 876, 12786, 197796, 3183156, 52718616, 892401426, 15368638836, 268388185596, 4741271556456, 84573471344916, 1521119577791976, 27554494253636136, 502257203287150896, 9205363627419463506
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Number of walks of length 2n on the 6-regular tree beginning and ending at some fixed vertex. Hankel transform is A135349. [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Feb 25 2009]
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FORMULA
| a(n) = Sum{k, 0<=k<=n}A039599(n,k)*5^(n-k). - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Aug 25 2007
Contribution 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)
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CROSSREFS
| Sequence in context: A173535 A004355 A124862 * A191096 A151832 A133306
Adjacent sequences: A130974 A130975 A130976 * A130978 A130979 A130980
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KEYWORD
| nonn
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Aug 23 2007
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EXTENSIONS
| More terms from Olivier Gerard (Sep 22 2007).
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