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 A070647 Largest prime factor of sequence of numbers of the form p*q (p, q distinct primes). 12
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n)=P(A006881(n)) where P(x) is the largest prime factor of x. EXAMPLE 6 = 2*3 is the first number of the form p*q (p, q distinct primes) hence a(1)=3. MATHEMATICA 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 (* Vladimir Joseph Stephan Orlovsky, Apr 10 2010 *) PROG (Haskell) a070647 = a006530 . a006881 -- Reinhard Zumkeller, Sep 23 2011 (PARI) go(x)=my(v=List()); forprime(p=2, sqrtint(x\1), forprime(q=p+1, x\p, listput(v, [p*q, q]))); apply(v->v[2], vecsort(Vec(v), 1)) \\ Charles R Greathouse IV, Sep 14 2015 CROSSREFS Cf. A006530, A084127, A195758. Sequence in context: A279399 A321784 A225889 * A070949 A222579 A141574 Adjacent sequences: A070644 A070645 A070646 * A070648 A070649 A070650 KEYWORD easy,nonn AUTHOR Benoit Cloitre, May 13 2002 STATUS approved

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Last modified January 28 22:08 EST 2023. Contains 359905 sequences. (Running on oeis4.)