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A130978
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G.f.: 12/(5 + 7*sqrt(1-24*x)).
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6
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1, 7, 91, 1435, 24955, 460747, 8859739, 175466347, 3553964155, 73266506635, 1532152991131, 32420721097387, 692865048943291, 14932919812627915, 324195908270339035, 7083228794200550635
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OFFSET
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0,2
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COMMENTS
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Number of walks of length 2n on the 7-regular tree beginning and ending at some fixed vertex. Hankel transform is A135314. - Philippe Deléham, Feb 25 2009
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LINKS
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FORMULA
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D-finite with recurrence: n*a(n) = (73*n-36)*a(n-1) - 588*(2*n-3)*a(n-2) . - Vaclav Kotesovec, Oct 20 2012
a(n) ~ 7*2^(3*n+1)*3^(n+1)/(25*sqrt(Pi)*n^(3/2)) . - Vaclav Kotesovec, Oct 20 2012
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MAPLE
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g:=12/(5+7*sqrt(1-24*x)); gser:=series(g, x=0, 20); seq(coeff(gser, x, n), n=0..15); # Emeric Deutsch, Aug 26 2007
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MATHEMATICA
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CoefficientList[Series[12/(5+7*Sqrt[1-24*x]), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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