

A028935


A006720(n)^3 (cubed terms of Somos4 sequence).


3



1, 1, 1, 1, 8, 27, 343, 12167, 205379, 30959144, 3574558889, 553185473329, 578280195945297, 238670664494938073, 487424450554237378792, 2035972062206737347698803, 4801616835579099275862827431
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OFFSET

0,5


COMMENTS

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^3x.


REFERENCES

B. Mazur, Arithmetic on curves, Bull. Amer Math. Soc. 14 (1986), 207259; see p 225.


LINKS

Table of n, a(n) for n=0..16.


FORMULA

P=(0, 0), 2P=(1, 0), if kP=(a, b) then (k+1)P=(a'=(b^2a^3)/a^2, b'=1b*a'/a).


EXAMPLE

5P = (1/4, 5/8).


CROSSREFS

Cf. A006720, A028945, A151502.
Sequence in context: A029792 A112993 A115694 * A030089 A007235 A029789
Adjacent sequences: A028932 A028933 A028934 * A028936 A028937 A028938


KEYWORD

nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

Edited by N. J. A. Sloane, May 14 2009


STATUS

approved



