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Search: id:A127553
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| A127553 |
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a(n) = Product_{k=1 to n} LCM(k,n)/GCD(k,n). |
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+0
9
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| 1, 2, 18, 96, 15000, 6480, 84707280, 41287680, 21427701120, 56700000000, 94121726392108800, 2483144294400, 11159820050604594969600, 24625709514114508800, 620634514500000000000, 359450793240158011392000
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n) = A071248(n)/A067911(n). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 03 2007
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EXAMPLE
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a(6) = LCM(1,6)/GCD(1,6) * LCM(2,6)/GCD(2,6) * LCM(3,6)/GCD(3,6) * LCM(4,6)/GCD(4,6) * LCM(5,6)/GCD(5,6) * LCM(6,6)/GCD(6,6) = 6/1 * 6/2 * 6/3 * 12/2 * 30/1 * 6/6 = 6480.
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MAPLE
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A067911 := proc(n) mul( gcd(k, n), k=1..n) ; end: A071248 := proc(n) mul( lcm(k, n), k=1..n) ; end: A127553 := proc(n) A071248(n)/A067911(n) ; end: for n from 1 to 30 do printf("%d, ", A127553(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 03 2007
a:=n->product(ilcm(k, n)/igcd(k, n), k=1..n): seq(a(n), n=1..18); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 13 2007
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CROSSREFS
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Cf. A056789.
Sequence in context: A036800 A052633 A052638 this_sequence A055357 A087291 A005969
Adjacent sequences: A127550 A127551 A127552 this_sequence A127554 A127555 A127556
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Apr 02 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 03 2007
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