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A055735 The x value of the unique nontrivial solution to x^3 + d y^3 = 1 for all admissible d < 50000. d = 2,7,9,17,...,48949. +0
1
-1, 2, -2, 18, -8, -19, 3, -3, 10, -7, 4, -4, 9, 5, -5, -17, 6, -6, 19, 7, -7, -15, 8, -8, 17, 361, -26, 9, -9, 28, 10, -10, 11, -11, -23, -35, -71, 12, -12, 73, 37, 25, 13, -13, 14, -14, -44, 15, -15, 46, -31, -63, 16, -16, 65, 33, 17, -17, 361, -53, 18, -18, 55, 19, -19, -39, 20, -20, 41, -62, 21, -21, 64, 22, -22, 23, -23 (list; graph; listen)
OFFSET

1,2

COMMENT

Theorem (Nagell-Delone): The equation x^3 + dy^3 = 1 has at most one nontrivial solution. If (e,f) is a solution, then e+f*d^(1/3) is either E or E^2, where E is the fundamental unit of Q adjoined with the cube root of d. The latter case occurs only for d = 19,20,28.

REFERENCES

H. C. Williams and R. Holte, Computation of the solution of x^3 + D y^3 = 1, Mathematics of Computation, Vol. 31, No. 139. (Jul., 1977), pp. 778-785.

EXAMPLE

(-1)^3 + 2*1^3 = 1, 2^3 + 7*(-1)^3 = 1, etc...

CROSSREFS

Sequence in context: A000528 A074970 A087338 this_sequence A100304 A096190 A136434

Adjacent sequences: A055732 A055733 A055734 this_sequence A055736 A055737 A055738

KEYWORD

nice,sign

AUTHOR

Matt Herman (Henayni(AT)hotmail.com), Nov 28 2000

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.


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