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A151889
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a(1)=2, a(2)=3; a(2k-1)=2a(2k-2)+a(2k-3), a(2k)=3a(2k-2)+2a(2k-3), k >= 2.
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1
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2, 3, 8, 13, 34, 55, 144, 233, 610, 987, 2584, 4181, 10946, 17711, 46368, 75025, 196418, 317811, 832040, 1346269, 3524578, 5702887, 14930352, 24157817, 63245986, 102334155, 267914296, 433494437, 1134903170, 1836311903
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OFFSET
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1,1
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LINKS
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FORMULA
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a(2k-1) = Fib(3k-1), a(2k) = Fib(3k).
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MATHEMATICA
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LinearRecurrence[{0, 4, 0, 1}, {2, 3, 8, 13}, 30] (* Harvey P. Dale, Dec 31 2021 *)
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PROG
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(PARI) a(n) = if (n==1, 2, if (n==2, 3, if (n%2, 2*a(n-1)+a(n-2), 3*a(n-2)+2*a(n-3)))) \\ Michel Marcus, Jun 20 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Antonia Redondo Buitrago (aredondo(AT)sabuco.com), Jul 23 2009
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STATUS
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approved
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