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Search: id:A132189
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| A132189 |
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Number of non-constant 3-term geometric progressions with no term exceeding n. |
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+0
3
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| 0, 0, 0, 2, 2, 2, 2, 4, 8, 8, 8, 10, 10, 10, 10, 16, 16, 20, 20, 22, 22, 22, 22, 24, 32, 32, 36, 38, 38, 38, 38, 44, 44, 44, 44, 54, 54, 54, 54, 56, 56, 56, 56, 58, 62, 62, 62, 68, 80, 88, 88, 90, 90, 94, 94, 96, 96, 96, 96, 98, 98, 98, 102, 116, 116, 116, 116, 118, 118, 118
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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In racetrack language, this is the number of trifectas in geometric progression in an n-horse race.
It appears that geometric progression like (k,0,0) are excluded. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
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REFERENCES
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Gerry Myerson, Trifectas in Geometric Progression, Australian Mathematical Society Gazette, 2008, to appear.
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MATHEMATICA
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a = {}; For[n = 1, n < 80, n++, c = 0; For[j = 1, j < n + 1, j++, For[h = 1, h < n + 1, h++, If[Not[h == j], If[IntegerQ[j*(h/j)^2], If[j*(h/j)^2 < n + 1, c++ ]]]]]; AppendTo[a, c]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
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CROSSREFS
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Sequence in context: A060824 A162799 A064849 this_sequence A034585 A147751 A045948
Adjacent sequences: A132186 A132187 A132188 this_sequence A132190 A132191 A132192
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KEYWORD
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nonn
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AUTHOR
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Gerry Myerson (gerry(AT)ics.mq.edu.au), Nov 21 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Nov 24 2007
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