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A114863
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Floor[n^(n/3)/n!!! ].
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0
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1, 0, 1, 1, 1, 2, 3, 3, 4, 7, 7, 10, 18, 18, 26, 45, 44, 64, 113, 112, 163, 287, 285, 416, 733, 731, 1067, 1885, 1885
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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COMMENTS
| This sequence is an approximation of a triple factorial analogue to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 3, 6.
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FORMULA
| a(n) = Floor[n^(n/3)/n!!! ]. a(n) = Floor[CubeRoot(A000312(n))/A007661(n)].
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EXAMPLE
| a(9) = Floor[(9^3)/162] = Floor[4.5] = 4.
a(10) = Floor[(10^3.33333)/280] = Floor[7.69381906] = 7.
a(27) = Floor[(27^9)/7142567040] = Floor[1067.62701] = 1067.
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CROSSREFS
| Cf. A000312, A006882, A055775, A007661.
Sequence in context: A119795 A119614 A035540 * A152980 A170891 A035535
Adjacent sequences: A114860 A114861 A114862 * A114864 A114865 A114866
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 20 2006
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