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A132421
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a(n) = LCM of the integers b(k), over all k where 1 <= k <= n, where b(k) = the k-th integer from among those positive integers which are coprime to (n+1-k).
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1
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1, 2, 3, 20, 420, 90, 1155, 6552, 990, 340340, 38798760, 406980, 314954640, 30630600, 489304530, 18357939600, 21649708080, 2872543794120, 181957885200, 5555594444400, 237972194460, 32681613985020, 378270916143120, 892567605600, 392636231914726800, 1707200400597892200, 1079806447472472720, 4176841288170450900
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| The integers coprime to 4 are 1,3,5,.. The first of these is 1. The integers coprime to 3 are 1,2,4,5,.. The 2nd of these is 2. The integers coprime to 2 are 1,3,5,7,9,.. The 3rd of these is 5. And the integers coprime to 1 are 1,2,3,4,5,.. The 4th of these is 4. So a(5) = LCM(1,2,5,4) = 20.
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CROSSREFS
| Cf. A130767.
Sequence in context: A177946 A006246 A110372 * A132500 A129411 A124447
Adjacent sequences: A132418 A132419 A132420 * A132422 A132423 A132424
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Aug 20 2007
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EXTENSIONS
| More terms from Sean A. Irvine (sairvin(AT)xtra.co.nz), Nov 25 2010
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