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A028941 Denominator of X-coordinate of n*P where P is generator for rational points on curve y^2+y = x^3-x. 1
1, 1, 1, 1, 4, 1, 9, 25, 49, 16, 529, 841, 3481, 16641, 98596, 4225, 2337841, 13608721, 67387681, 264517696, 6941055969, 12925188721, 384768368209, 5677664356225, 61935294530404, 49020596163841, 16063784753682169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Squares of terms in A006769 (or A006720).

REFERENCES

G. Everest, A. J. van der Poorten, I. Shparlinski and T. Ward, Recurrence Sequences: Examples and Applications, AMS Monographs, 2003

B. Mazur, Arithmetic on curves, Bull. Amer Math. Soc. 14 (1986), 207-259; see p 225.

LINKS

Table of n, a(n) for n=1..27.

FORMULA

This sequence satisfies the quadratic recurrence relation a(n)a(n-6)=-a(n-1)a(n-5)+2a(n-2)a(n-4)+2a(n-3)^2 which is a generalized Somos-6 relation. - Graham Everest (g.everest(AT)uea.ac.uk), Dec 16 2002

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).

CROSSREFS

Sequence in context: A143763 A128626 A193963 * A176080 A065045 A185088

Adjacent sequences:  A028938 A028939 A028940 * A028942 A028943 A028944

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 20 13:52 EDT 2014. Contains 240806 sequences.