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Search: id:A073459
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| 5, 16, 40, 98, 241, 591, 1393, 3386, 8313, 20393, 50189, 123972, 308917, 776173, 1953900, 4942615, 12556599, 32045879, 82012870, 210587095, 542262360, 1400124552, 3623612454, 9398492120, 24425121427, 63595807021, 165867439024
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Smallest k such that prime(k) > n*composite(k).
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EXAMPLE
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n=39: p(39)=167, c(39)=56, q=2.98; n=40: p(40)=173, c(40)=57, q=3.035, so a(3)=40.
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MATHEMATICA
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f[x_] := Floor[Prime[x] / FixedPoint[x + PrimePi[ # ] + 1 &, x]]; t=Table[0, {30}]; Do[ s = f[n]; If[ s < 31 && t[[s]]==0, t[[s]] = n], {n, 1000000}]; t
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PROGRAM
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(PARI) nextcomposite(k)=if(k<3, 4, if(isprime(k), k+1, k));
(PARI) k=1; p=2; q=4; for(n=1, 19, while(p<=n*q, p=nextprime(p+1); q=nextcomposite(q+1); k++); print1(k, ", "))
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CROSSREFS
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Cf. A000040, A002808, A073458.
Adjacent sequences: A073456 A073457 A073458 this_sequence A073460 A073461 A073462
Sequence in context: A099452 A006007 A001753 this_sequence A081997 A078449 A014161
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Aug 02 2002
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EXTENSIONS
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Terms a(12) to a(19) and PARI code from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 26 2004
Terms a(20) to a(27) from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 28 2004
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