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Search: id:A082485
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| A082485 |
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Numbers n such that 1/(2-s(n)) is an integer where s(k)=sum(i=1,k,1/3^floor(sqrt(i))). |
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+0
1
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| 3, 11, 21, 33, 47, 63, 83, 105, 129, 155, 183, 213, 245, 279, 315, 353, 393, 435, 479, 525, 573, 623, 675, 731, 789, 849, 911, 975, 1041, 1109, 1179, 1251, 1325, 1401, 1479, 1559, 1641, 1725, 1811, 1899, 1989
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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For any rational x=p/q > 1: L(x)=sum(i>=1,1/x^floor(sqrt(i))) is rational; i.e. L(4)=11/9, L(5)=7/8, L(7/3)=27/8.... L(x)=1 for an irrational value, namely : x=5/2+sqrt(17)/2.
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FORMULA
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s(a(n))=2-1/3^n
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CROSSREFS
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Sequence in context: A031239 A088619 A031318 this_sequence A064568 A034185 A129215
Adjacent sequences: A082482 A082483 A082484 this_sequence A082486 A082487 A082488
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 27 2003
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