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Search: id:A114853
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| 1, 2, 9, 32, 208, 972, 7843, 43690, 409968, 2604166, 27447010, 193491763
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OFFSET
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1,2
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COMMENT
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This is to double factorial A006882 as A055775 "Floor(n^n/n!)" is to factorial. This sequence is a weak first approximation of a double factorial analogue to Stirling's approximation to factorial. Note that a(n) is exact for n = 1, 2, 3, 4, 6.
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FORMULA
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a(n) = Floor[n^n/n!! ]. a(n) = Floor[A000312(n)/A006882(n)].
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EXAMPLE
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a(10) = Floor[(10^10)/3840] = Floor[2604166.67] = 2604166.
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CROSSREFS
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Cf. A000312, A006882, A055775.
Sequence in context: A026526 A086607 A013501 this_sequence A110376 A036505 A056916
Adjacent sequences: A114850 A114851 A114852 this_sequence A114854 A114855 A114856
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 20 2006
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