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Search: id:A038625
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| A038625 |
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a(n) is smallest number m such that m = n*pi(m), where pi(k) = number of primes <= k (A000720). |
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5
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| 2, 27, 96, 330, 1008, 3059, 8408, 23526, 64540, 175197, 480852, 1304498, 3523884, 9557955, 25874752, 70115412, 189961182, 514272411, 1394193580, 3779849598, 10246935644, 27788566029, 75370121160, 204475052375, 554805820556
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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Golomb shows that solutions exist for each n>1.
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REFERENCES
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S. W. Golomb, On the Ratio of N to pi(N), American Mathematical Monthly, 69 (1962), 36-37.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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It appears that a(n) is asymptotic to e^2*exp(n). - Chris Caldwell, Apr 02 2008
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EXAMPLE
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pi(3059) = 437 and 3059/437 = 7, so a(7)=3059
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MAPLE
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with(numtheory); f:=proc(n) local i; for i from 2 to 10000 do if i mod pi(i) = 0 and i/pi(i) = n then RETURN(i); fi; od: RETURN(-1); end; - N. J. A. Sloane (njas(AT)research.att.com), Sep 01 2008
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CROSSREFS
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Cf. A000720, A038623-A038627, A073436.
Sequence in context: A094680 A061192 A041883 this_sequence A041801 A166942 A119351
Adjacent sequences: A038622 A038623 A038624 this_sequence A038626 A038627 A038628
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KEYWORD
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nonn
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AUTHOR
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Jud McCranie (j.mccranie(AT)comcast.net)
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EXTENSIONS
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Three more terms from Labos E. (labos(AT)ana.sote.hu), Sep 12 2003
Edited by N. J. A. Sloane (njas(AT)research.att.com) at the suggestion of Chris Caldwell, Apr 08 2008
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