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Search: id:A093683
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| A093683 |
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Number of pairs of twin primes whose larger element is <= 10^n-th prime. |
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+0
3
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OFFSET
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1,1
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COMMENT
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This sequence is >= the values of pi(x): 4, 25, 168, 1229, . . . x in A006880
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REFERENCES
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Enoch Haga, "Wandering through a prime number desert," Table 6, in Exploring prime numbers on your PC and the Internet, 2001 (ISBN 1-885794-17-7)
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LINKS
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Author? Twin prime count
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FORMULA
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Count twin primes below p10^n: 10th prime, 100th prime, etc.
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EXAMPLE
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a(5)=10250 because that is the number of twin primes below 1299709, the 100000-th prime
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MATHEMATICA
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NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; c = 0; p = q = 1; Do[l = Prime[10^n]; While[q <= l, If[p + 2 == q, c++ ]; p = q; q = NextPrim[p]]; Print[c], {n, 12}] (from Robert G. Wilson v Apr 10 2004)
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CROSSREFS
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See A049035 for another version. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 05 2008]
Cf. A006880 A007508 A049035.
Sequence in context: A140177 A034494 A084210 this_sequence A006348 A051820 A166697
Adjacent sequences: A093680 A093681 A093682 this_sequence A093684 A093685 A093686
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KEYWORD
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nonn
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net), Apr 09 2004
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