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A047694
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x such that y^2=C(x,0)+C(x,1)+C(x,2)+C(x,3) is soluble.
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1
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OFFSET
| 0,3
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REFERENCES
| R. K. Guy, Unsolved Problems in Number Theory, Section D3.
W. Ljunggren, A diophantine problem, J. London Math. Soc. (2), 3 (1971), p. 385-391.
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LINKS
| Andrew Bremner, An equation of Mordell, Math. Comp., 29 (1975), p. 925-928.
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FORMULA
| x such that 6y^2 = (x + 1)(x^2 - x + 6) has solutions in integers.
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MATHEMATICA
| Select[Range[-10, 10^3], IntegerQ[Sqrt[((# + 1)(#^2 - # + 6))/6]] &] (* From Alonso del Arte, Sep 13 2011 *)
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CROSSREFS
| Cf. A047695.
Sequence in context: A096690 A050612 A120110 * A129666 A135781 A167236
Adjacent sequences: A047691 A047692 A047693 * A047695 A047696 A047697
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KEYWORD
| sign,fini,full,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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