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A028936
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Numerator of x-coordinate of (2n)*P where P is the generator for rational points on the curve y^2 + y = x^3 - x.
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4
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1, 2, 6, 21, 161, 1357, 18526, 480106, 12551561, 683916417, 51678803961, 4881674119706, 997454379905326, 213822353304561757, 79799551268268089761, 53139223644814624290821, 36631192030206080565822006, 54202648602164057575419038802
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OFFSET
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1,2
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LINKS
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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).
0 = a(n)*a(n+6) - 5*a(n+1)*a(n+5) + 4*a(n+2)*a(n+4) - 20*a(n+3)^2 for all n in Z. a(n) = A006720(n+1)*A006720(n+2). - Michael Somos, Apr 12 2020
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EXAMPLE
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4P =(2, -3).
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PROG
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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