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A317053
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Complete list of solutions to y^2 + y = x^3 - 525x + 10156 with y > 0; sequence gives positive y values.
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0
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31, 74, 76, 87, 112, 121, 319, 562, 679, 1462, 3937, 5312, 7987, 18312, 61312, 66712, 2597287
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OFFSET
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1,1
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COMMENTS
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This equation gives the elliptic curve (W46) studied by Stroeker and de Weger. This curve has rank 3 with generators P1 = (25, 112), P2 = (-20, 112) and P3 = (70, 562). The list gives all integer points with y > 0 in this curve.
Each positive y corresponds to a negative solution -y - 1, so that the sequence gives all y values of solutions.
Some y values corresponds to three solutions. For y = 87, we have x = -25, 5 or 20. For y = 112, we have x = -20, -5 or 25. Any other value of y corresponds to a unique solution.
This equation can be transformed to A000332(n) = A000579(m) by x = (15/2)m^2 - (75/2)m + 25 and y = (225/2)n^2 - (675/2)n + 112. Hence, A000332(n) = A000579(m) (n >= 4, m >= 6) has no integer solutions other than (n, m)= (4, 6) and (10, 10).
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LINKS
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EXAMPLE
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a(1) = 31: (-29)^3 - 525 * (-29) + 10156 = 996 = 31 * 32.
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PROG
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(SageMath) EllipticCurve([0, 0, 1, -525, 10156]).integral_points()
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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