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Search: id:A110077
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| A110077 |
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a(n) is the smallest number m such that sigma(m)=10^n and if there is no such m, a(n)=0. |
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3
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| 1, 0, 0, 0, 8743, 71193, 640737, 5906061, 65624979, 590624811, 5498542791, 55995364341
(list; graph; listen)
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OFFSET
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0,5
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COMMENT
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A110078(n) gives number of solutions of the equation sigma(x)=10^n. Conjecture: For n>3 a(n) is positive.
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EXAMPLE
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a(9)=590624811 because sigma(590624811)=sigma(3^3*7*3124999) sigma(3^3)*sigma(7)*sigma(3124999)=40*8*3125000=10^9 and 590624811 is the smallest number m with this property (sigma(m)=10^9).
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CROSSREFS
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Cf. A110076, A110078.
Sequence in context: A115614 A165630 A067867 this_sequence A061665 A156083 A031791
Adjacent sequences: A110074 A110075 A110076 this_sequence A110078 A110079 A110080
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KEYWORD
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more,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 01 2005
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EXTENSIONS
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a(10)-a(11) from Donovan Johnson (donovan.johnson(AT)yahoo.com) and Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 22 2008
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