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A028935
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A006720(n)^3 (cubed terms of Somos-4 sequence).
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3
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1, 1, 1, 1, 8, 27, 343, 12167, 205379, 30959144, 3574558889, 553185473329, 578280195945297, 238670664494938073, 487424450554237378792, 2035972062206737347698803, 4801616835579099275862827431
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OFFSET
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0,5
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COMMENTS
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If initial two 1's are omitted, denominator of y coordinate of (2n+1)*P where P is generator for rational points on curve y^2+y = x^3-x.
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REFERENCES
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B. Mazur, Arithmetic on curves, Bull. Amer Math. Soc. 14 (1986), 207-259; see p 225.
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LINKS
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Table of n, a(n) for n=0..16.
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FORMULA
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P=(0, 0), 2P=(1, 0), if kP=(a, b) then (k+1)P=(a'=(b^2-a^3)/a^2, b'=1-b*a'/a).
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EXAMPLE
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5P = (1/4, -5/8).
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CROSSREFS
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Cf. A006720, A028945, A151502.
Sequence in context: A029792 A112993 A115694 * A030089 A007235 A029789
Adjacent sequences: A028932 A028933 A028934 * A028936 A028937 A028938
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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Edited by N. J. A. Sloane, May 14 2009
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STATUS
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approved
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