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A137626
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The largest prime in the first set of n consecutive primes for which p+4 is semiprime.
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3
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5, 31, 181, 733, 1777, 8363, 8369, 19273, 175333, 175349, 33952819
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OFFSET
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1,1
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COMMENTS
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a(n) = last prime in the first run of n primes such that p+4 is semiprime for each prime p in the run. [Sean A. Irvine, Feb 13, 2012.]
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LINKS
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Table of n, a(n) for n=1..11.
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EXAMPLE
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a(2)=31 is the largest in a set of 2 consecutive primes {29,31}, and 29+4=33=3*11 and 31+4=35=5*7 are both semiprime. No smaller number has this property.
59 is not in the sequence because although 47+4=51=3*17 and 53+4=57=3*19 are both semiprime, 59+4=63=3*3*7 is not.
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CROSSREFS
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Cf. A001358 A137625 A137627 A137628.
Sequence in context: A034353 A180635 A078526 * A202753 A057426 A015540
Adjacent sequences: A137623 A137624 A137625 * A137627 A137628 A137629
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KEYWORD
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more,nonn
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AUTHOR
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Enoch Haga, Jan 30 2008
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EXTENSIONS
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a(11) from Sean A. Irvine, Feb 12 2012
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STATUS
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approved
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