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A164619
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Integers of the form A164577(k)/3.
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0
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4, 15, 54, 75, 132, 169, 320, 459, 735, 847, 1104, 1250, 1764, 2175, 2904, 3179, 3780, 4107, 5200, 6027, 7425, 7935, 9024, 9604, 11492, 12879, 15162, 15979, 17700, 18605, 21504, 23595, 26979, 28175, 30672, 31974, 36100, 39039, 43740, 45387, 48804
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The sequence members are the third of the average of a set of smallest cubes, if integer.
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FORMULA
| a(n)= +2*a(n-1) -a(n-2) -a(n-3) +2*a(n-4) -a(n-5) +2*a(n-6) -4*a(n-7) +2*a(n-8) +2*a(n-9) -4*a(n-10) +2*a(n-11) -a(n-12) +2*a(n-13) -a(n-14) -a(n-15) +2*a(n-16) -a(n-17). - R. J. Mathar, Jan 25 2011
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EXAMPLE
| A third of the average of the first cube, A164577(1)/3=1/3, is not integer and does not contribute to the sequence.
A third of the average of the first two cubes, A164577(2)/3=4, is integer and defines a(1)=4 of the sequence.
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MATHEMATICA
| s=0; lst={}; Do[a=(s+=(n^3)/3)/n; If[Mod[a, 1]==0, AppendTo[lst, a]], {n, 2*5!}]; lst
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CROSSREFS
| Cf. A050248, A051456, A078617, A078618, A136116, A154293, A164286, A164576, A164577, A164578, A164579
Sequence in context: A162978 A171309 A071719 * A090326 A006234 A094821
Adjacent sequences: A164616 A164617 A164618 * A164620 A164621 A164622
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KEYWORD
| nonn
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AUTHOR
| Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 17 2009
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EXTENSIONS
| Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 20 2009
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