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A070647
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Largest prime factor of sequence of numbers of the form p*q (p, q distinct primes).
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8
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3, 5, 7, 5, 7, 11, 13, 11, 17, 7, 19, 13, 23, 17, 11, 19, 29, 31, 13, 23, 37, 11, 41, 17, 43, 29, 13, 31, 47, 19, 53, 37, 23, 59, 17, 61, 41, 43, 19, 67, 47, 71, 13, 29, 73, 31, 79, 53, 23, 83, 59, 89, 61, 37, 17, 97, 67, 101, 29, 41, 103, 19, 71, 107, 43, 31, 109, 73, 17
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OFFSET
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1,1
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LINKS
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_Reinhard Zumkeller_, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n)=P(A006881(n)) where P(x) is the largest prime factor of x.
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EXAMPLE
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6=2*3 is the first number of the form p*q (p, q distinct primes) hence a(1)=3
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MATHEMATICA
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f[n_]:=Last/@FactorInteger[n]=={1, 1}; f1[n_]:=Min[First/@FactorInteger[n]]; f2[n_]:=Max[First/@FactorInteger[n]]; lst={}; Do[If[f[n], AppendTo[lst, f2[n]]], {n, 0, 6!}]; lst [From Vladimir Joseph Stephan Orlovsky, Apr 10 2010]
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PROG
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(Haskell)
a070647 = a006530 . a006881 -- Reinhard Zumkeller, Sep 23 2011
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CROSSREFS
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Cf. A006530, A084127, A195758.
Sequence in context: A186702 A141710 A225889 * A070949 A222579 A141574
Adjacent sequences: A070644 A070645 A070646 * A070648 A070649 A070650
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre, May 13 2002
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STATUS
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approved
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