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A006646
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Exponential self-convolution of Pell numbers.
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3
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0, 0, 2, 12, 64, 320, 1568, 7616, 36864, 178176, 860672, 4156416, 20070400, 96911360, 467935232, 2259402752, 10909384704, 52675215360, 254338531328, 1228055248896, 5929575645184, 28630524624896
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = ((2+sqrt(8))^n+(2-sqrt(8))^n-2^(n+1))/8; E.g.f.: exp(2x)(sinh(sqrt(2)*x))^2/2 = (exp(x)*sinh(sqrt(2)*x)/sqrt(2))^2. - Paul Barry, May 16 2003
G.f.: 2*x^2 / ( (2*x-1)*(4*x^2+4*x-1) ). - R. J. Mathar, Nov 24 2012
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MATHEMATICA
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PROG
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(Magma) [Floor(((2+Sqrt(8))^n+(2-Sqrt(8))^n-2^(n+1))/8): n in [0..30] ]; // Vincenzo Librandi, Aug 20 2011
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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