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A126786
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a(n) = n-th positive divisor of ((2n)!/n!^2).
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0
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1, 2, 4, 7, 6, 7, 11, 11, 20, 34, 17, 34, 25, 19, 19, 34, 27, 25, 25, 26, 33, 41, 36, 45, 47, 49, 98, 62, 40, 86, 88, 82, 57, 65, 67, 148, 142, 67, 92, 134, 61, 66, 56, 68, 71, 68, 63, 71, 83, 97, 106, 134, 77, 95, 166, 186, 222, 183, 113, 119, 103, 103, 107, 178, 134, 164
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| (2*5)!/5!^2 = 252. The divisors of 252 are 1, 2, 3, 4, 6, 7, 9, 12, 14, 18, 21, 28, 36, 42, 63, 84, 126, 252. The 5th of these is 6. So a(5) = 6.
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MATHEMATICA
| f[n_] := Divisors[(2n)!/n!^2][[n]]; Array[f, 66] (*Chandler*)
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CROSSREFS
| Cf. A000984.
Sequence in context: A035311 A129980 A198137 * A154614 A161211 A161368
Adjacent sequences: A126783 A126784 A126785 * A126787 A126788 A126789
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Feb 18 2007
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 26 2007
More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 25 2007
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