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Search: id:A111499
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| A111499 |
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Floor of 10^n/Pi(10^n) - 1. |
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+0
1
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| 1, 3, 4, 7, 9, 11, 14, 16, 18, 20, 23, 25, 27, 30, 32, 34, 37, 39, 41, 44, 46, 48, 50
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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10^n/Pi(10^n) - 1) is the ratio of the number of composite numbers less than 10^n divided by the number of prime numbers less than 10^n. Conjecture: Except for the first 2 terms, the difference between successive terms is 2 or 3.
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LINKS
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XavierGourdon, Numbers, Constants and computations.
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FORMULA
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Pi(n) is the number of primes less than or equal to n.
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MATHEMATICA
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f[n_] := Floor[10^n/PrimePi[10^n] - 1]; Table[ f[n], {n, 14}] (* Robert G. Wilson v *)
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PROGRAM
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(PARI) PiRatio(m, n) = \ Good only up to 10^9 { local(x, p1, p2, a, b); for(x=m, n, p1=10^x; a=floor(p1/primepi(p1)-1); print1(a, ", ") ) }
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CROSSREFS
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Sequence in context: A019990 A047544 A035267 this_sequence A077025 A032729 A035270
Adjacent sequences: A111496 A111497 A111498 this_sequence A111500 A111501 A111502
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Nov 16 2005
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EXTENSIONS
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a(23) from Robert G. Wilson v (rgwv(at)rgwv.com), Nov 18 2005
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