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A336030
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a(n) = Fibonacci(n-1) + Fibonacci(floor(n/2)).
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1
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1, 0, 2, 2, 3, 4, 7, 10, 16, 24, 39, 60, 97, 152, 246, 390, 631, 1008, 1631, 2618, 4236, 6820, 11035, 17800, 28801, 46512, 75258, 121626, 196795, 318188, 514839, 832650, 1347256, 2179296, 3526175, 5704484, 9230049, 14932936, 24161998, 39092350, 63252751, 102340920
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OFFSET
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0,3
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COMMENTS
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For n>=2, a(n) is the number of oriented rational links with crossing number n and deficiency 0.
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LINKS
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FORMULA
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G.f.: -(3*x^4-x^3+x-1)/((x^2+x-1)*(x^4+x^2-1)). - Alois P. Heinz, Jul 07 2020
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PROG
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(PARI) a(n) = fibonacci(n-1) + fibonacci(n\2);
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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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