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A110224
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a(n) = Fibonacci(n)^3 + Fibonacci(n+1)^3.
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5
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1, 2, 9, 35, 152, 637, 2709, 11458, 48565, 205679, 871344, 3690953, 15635321, 66231970, 280563633, 1188485803, 5034507976, 21326515877, 90340574445, 382688808866, 1621095817661, 6867072066967, 29089384105824
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: (1 - x - 3*x^2 - x^3)/(1 - 3*x - 6*x^2 + 3*x^3 + x^4) = (1 - x - 3*x^2 - x^3)/((1 + x - x^2)*(1 - 4x - x^2)).
a(n) = 3*a(n-1) + 6*a(n-2) - 3*a(n-3) - a(n-4).
a(n) = (3*(-1)^n*Fibonacci(n-1) + 2*Fibonacci(3*n+2))/5.
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MATHEMATICA
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Total/@Partition[Fibonacci[Range[0, 30]]^3, 2, 1] (* or *) LinearRecurrence [{3, 6, -3, -1}, {1, 2, 9, 35}, 30] (* Harvey P. Dale, May 29 2013 *)
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PROG
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(Magma) [Fibonacci(n)^3 + Fibonacci(n+1)^3: n in [0..30]]; // Vincenzo Librandi, Jun 05 2011
(Sage) [sum(fibonacci(n+k)^3 for k in (0..1)) for n in (0..30)] # G. C. Greubel, Mar 18 2019
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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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