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A097134
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a(n) = 3*Fibonacci(2*n) + 0^n.
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5
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1, 3, 9, 24, 63, 165, 432, 1131, 2961, 7752, 20295, 53133, 139104, 364179, 953433, 2496120, 6534927, 17108661, 44791056, 117264507, 307002465, 803742888, 2104226199, 5508935709, 14422580928, 37758807075, 98853840297, 258802713816
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OFFSET
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0,2
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COMMENTS
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Image of 1/(1-3x) under the mapping g(x)->g(x/(1+x^2)). - Paul Barry, Jan 16 2005
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LINKS
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FORMULA
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G.f.: (1+x^2)/(1-3*x+x^2).
a(n) = 3*a(n-1) - a(n-2) for n > 2.
a(n) = Sum_{k=0..n} binomial(n, k)*(3*Fibonacci(k)+(-1)^k).
a(n) = Sum_{k=0..floor(n/2)} binomial(n-k-1,k)*(-1)^k*3^(n-2*k). - Paul Barry, Jan 16 2005
a(n) = Fibonacci(n+2)^2 - Fibonacci(n-2)^2. - Gary Detlefs, Dec 03 2010
a(n) = Fibonacci(6*n) - 5*Fibonacci(2*n)^3 for n > 0. - Gary Detlefs, Oct 18 2011
E.g.f.: 1 + 6*exp(3*x/2)*sinh(sqrt(5)*x/2)/sqrt(5). - Stefano Spezia, Aug 19 2019
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PROG
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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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