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A165904
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Somos-4 recurrence with a(i)=2^i for 0<=i<=3.
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2
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1, 2, 4, 8, 32, 96, 448, 2944, 15104, 160768, 1565696, 16812032, 341250048, 5081473024, 128940408832, 4153114198016, 110562817540096, 6199850375708672, 294499013825921024, 17095312584100282368, 1743063839902067064832
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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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a(n) = (a(n-1)*a(n-3) + a(n-2)^2)/a(n-4). - G. C. Greubel, Sep 18 2018
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MATHEMATICA
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RecurrenceTable[{a[n] == (a[n-1]*a[n-3] +a[n-2]^2)/a[n-4], a[0] == 1, a[1] == 2, a[2] == 4, a[3] == 8}, a, {n, 0, 30}] (* G. C. Greubel, Sep 18 2018 *)
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PROG
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(PARI) a(n)=if(n<4, [1, 2, 4, 8][n+1], (a(n-1)*a(n-3)+a(n-2)^2)/a(n-4))
(Magma) I:=[1, 2, 4, 8]; [n le 4 select I[n] else (Self(n-1)*Self(n-3) + Self(n-2)^2)/Self(n-4): n in [1..30]]; // G. C. Greubel, Sep 18 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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