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Search: id:A110901
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| A110901 |
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Product{k=1..n} (A013929(k)), the product of the first n positive integers which are each divisible by at least one square >= 4. |
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1
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| 4, 32, 288, 3456, 55296, 995328, 19906560, 477757440, 11943936000, 322486272000, 9029615616000, 288947699712000, 10402117189632000, 416084687585280000, 18307726253752320000, 823847681418854400000, 39544688708105011200000
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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Since 4, 8, 9 and 12 are the first 4 non-squarefree positive integers, the fourth
term of the sequence is 4*8*9*12 = 3456.
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MATHEMATICA
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Rest[ FoldList[ Times, 1, Select[ Range[2, 48], (Union[Last /@ FactorInteger[ # ]][[ -1]] > 1) == True &]]] (* Robert G. Wilson v *)
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PROGRAM
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(PARI) a=1; for(n=1, 48, if(!issquarefree(n), print1(a=a*n, ", ")))
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CROSSREFS
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Cf. A013929, A111059.
Sequence in context: A065089 A113329 A145710 this_sequence A000766 A047734 A060174
Adjacent sequences: A110898 A110899 A110900 this_sequence A110902 A110903 A110904
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Oct 09 2005
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EXTENSIONS
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More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and Robert G. Wilson v (rgwv(at)rgwv.com), Oct 11 2005
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