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A135796
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Numbers of the form 4x^3y+4y x^3 (where x,y are positive integers).
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3
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8, 40, 120, 128, 272, 312, 520, 640, 648, 888, 1160, 1200, 1400, 1920, 2040, 2048, 2080, 2952, 2968, 3240, 3280, 4040, 4352, 4872, 4992, 5000, 5368, 6120, 6960, 7008, 7280, 7320, 8320, 8840, 9720
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Squares of these numbers are of the form N^4-M^2 (where N belongs to A135786 and M to A135797) Proof uses: (4x^3y+4xy^3)^2=(x^2-y^2)^4+(x^4+6x^2y^2+y^4)^2
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MATHEMATICA
| a = {}; Do[Do[w = 4x^3y + 4x y^3; If[w < 10000, AppendTo[a, w]], {x, y, 1000}], {y, 1, 1000}]; Union[a] (*Artur Jasinski*)
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CROSSREFS
| Cf. A000404, A050803, A057102, A135784, A060803, A135786, A135787, A135789, A135790, A135791, A135792, A135793, A135795, A135796, A135797.
Sequence in context: A069083 A014642 A143943 * A105374 A162668 A191903
Adjacent sequences: A135793 A135794 A135795 * A135797 A135798 A135799
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Nov 29 2007
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