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Search: id:A066064
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| A066064 |
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a(n) = pq in decimal notation where p = prime(n) and q is the smallest prime (A066065(n)) such that p.q is a prime. |
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+0
2
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| 23, 37, 53, 73, 113, 137, 173, 193, 233, 293, 313, 373, 4111, 433, 4723, 5323, 593, 613, 673, 7129, 733, 797, 8311, 8923, 977, 1013, 1033, 10711, 1093, 11311, 1277, 13147, 1373, 13913, 1493, 15131, 15731, 1637, 16729, 1733, 17911, 18119, 1913
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
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A000040(2) = 3 and as 32, 33 and 35 are composite, the next prime 7 = A066065(2) yields a(2) = 37.
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PROGRAM
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(PARI) digitsIn(x)= { local(d); if (x==0, return(1)); d=1 + log(x)\log(10); if (10^d == x, d++, if (10^(d-1) > x, d--)); return(d) } Concat(a, b)= { return(a*10^digitsIn(b) + b) } { for (n = 1, 1000, p=prime(n); q=2; while(!isprime(c=Concat(p, q)), q=nextprime(q + 1)); write("b066064.txt", n, " ", c) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Nov 09 2009]
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CROSSREFS
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Sequence in context: A019549 A129800 A105184 this_sequence A163759 A092622 A129351
Adjacent sequences: A066061 A066062 A066063 this_sequence A066065 A066066 A066067
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KEYWORD
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base,nonn,new
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 01 2001
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