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Search: id:A071872
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| A071872 |
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Number of positive k such that k*tau(k) <= n. |
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+0
1
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| 0, 2, 1, 1, 3, 2, 4, 3, 3, 3, 5, 4, 6, 5, 7, 6, 6, 6, 6, 6, 6, 6, 8, 7, 9, 8, 10, 11, 10, 10, 10, 10, 12, 11, 13, 12, 12, 12, 14, 13, 15, 14, 14, 14, 14, 14, 16, 15, 15, 15, 15, 15, 15, 15, 15, 15, 17, 16, 18, 17, 19, 18, 20, 19, 19, 19, 19, 19, 19, 19, 19, 19, 21, 20, 22, 23, 22, 22
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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For n > 80, does always a(n) > Pi(n) the primes counting function ?
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PROGRAM
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(PARI) for(n=1, 100, print1(sum(i=1, n, if(sign(n-i*numdiv(i))-1, 0, 1))+sum(i=1, n, if(n-i*numdiv(i)-1, 0, 1)), ", "))
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CROSSREFS
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Sequence in context: A059779 A049346 A117334 this_sequence A141038 A156309 A093623
Adjacent sequences: A071869 A071870 A071871 this_sequence A071873 A071874 A071875
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 09 2002
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