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A168492
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Sequence with Hankel transform equal to 3^floor(n^2/2).
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3
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1, 1, 2, 7, 38, 250, 1748, 12463, 89606, 647710, 4702844, 34286038, 250928732, 1843209556, 13586564072, 100479347647, 745418148806, 5546324817718, 41382983725292, 309586136922898, 2321772733668980, 17453199438926188, 131489046194284568, 992678648890643206
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OFFSET
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0,3
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COMMENTS
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Hankel transform is A168493 (a trivial Somos-4 sequence linked to y^2=1-16x+76x^2-96x^3).
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LINKS
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FORMULA
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G.f.: 1/(1-x/(1-x/(1-3x/(1-3x/(1-x/(1-x/(1-3x/(1-3x/(1-x/(1-x/(1-3x/(1-.... (continued fraction);
G.f.: 1/(1-x-x^2/(1-4x-9x^2/(1-4x-x^2/(1-4x-9x^2/(1-4x-x^2/(1-4x-9x^2/(1-... (continued fraction);
G.f.: (1-2*x-sqrt((1-2*x)*(1-14*x+48*x^2)))/(6*x*(1-2*x)).
Recurrence: (n+1)*a(n) = 2*(8*n-3)*a(n-1) - 4*(19*n-31)*a(n-2) + 48*(2*n-5)* a(n-3). - Vaclav Kotesovec, Oct 20 2012
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MATHEMATICA
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CoefficientList[Series[(1-2*x-Sqrt[(1-2*x)(1-14*x+48*x^2)])/(6*x*(1-2*x)), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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