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Search: id:A121881
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| A121881 |
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a(n) = (4*a(n - 1)a(n - 3) + a(n - 2)^2)/a(n - 4). |
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+0
1
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| 1, 1, 1, 1, 5, 21, 109, 2621, 46409, 1290665, 143900249, 10827502009, 1650671059149, 826986635160509, 267834927512726725, 226491424023176449909, 497347467521206399078801, 706331193237960728379843409
(list; graph; listen)
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OFFSET
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1,5
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REFERENCES
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A. N. W. Hone, Algebraic curves, integer sequences and a discrete Painleve transcendent, Proceedings of SIDE 6, Helsinki, Finland, 2004.
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MATHEMATICA
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a[n_] := a[n] = (4*a[n - 1]a[n - 3] + a[n - 2]^2)/a[n - 4]; a[0] = 1; a[1] = 1; a[2] = 1; a[3] = 1; Table[a[n], {n, 0, 30}]
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CROSSREFS
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Cf. Somos-4 sequence A006720, A014125, A095708.
Sequence in context: A046633 A097175 A100284 this_sequence A041321 A082428 A015558
Adjacent sequences: A121878 A121879 A121880 this_sequence A121882 A121883 A121884
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KEYWORD
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nonn
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 09 2006
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EXTENSIONS
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Edited by njas, Sep 15 2006
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