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A160709
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Centuries containing a prime number of primes.
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1
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5, 14, 15, 20, 26, 30, 33, 35, 37, 39, 40, 45, 52, 55, 56, 60, 62, 63, 66, 70, 73, 75, 81, 87, 88, 89, 91, 93, 94, 96, 97, 98, 101, 108, 112, 115, 120, 122, 125, 131, 135, 140, 143, 155, 157, 166, 167, 168, 171, 175, 182, 183, 184, 185, 188, 189, 191, 192, 193, 196
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| H. v. Eitzen, Table of n, a(n) for n=1..10000
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FORMULA
| {n: A038822(n) is in A000040}.
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EXAMPLE
| a(1) = 5 because 5 is the first Century to have a prime number (17) of primes.
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MAPLE
| A038822 := proc(n) numtheory[pi](n*100)-numtheory[pi]((n-1)*100) ; end: A160709 := proc(n) option remember ; local a; if n = 1 then 5 ; else for a from procname(n-1)+1 do if isprime( A038822(a) ) then RETURN(a) ; fi; od: fi; end: seq(A160709(n), n=1...90) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 27 2009]
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MATHEMATICA
| Select[Range[200], PrimeQ[PrimePi[100#]-PrimePi[100(#-1)]]&] (* From Harvey P. Dale, Oct 03 2011 *)
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CROSSREFS
| Cf. A000040, A038822.
Sequence in context: A168213 A175485 A174657 * A067113 A101774 A196366
Adjacent sequences: A160706 A160707 A160708 * A160710 A160711 A160712
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), May 25 2009
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), May 25 2009
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 27 2009
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