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 A086410 Smallest prime factor of 3-smooth numbers, with a(1)=1. 5
 1, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = A020639(A003586(n)); a(n) <= A086411(n) <= 3. a(A033845(n)) = A086411(A033845(n))-1; a(A006899(n)) = A086411(A006899(n)). [Reinhard Zumkeller, Sep 25 2008] LINKS MATHEMATICA Reap[For[n = 1, n <= 2*10^5, n++, If[EulerPhi[6*n] == 2*n, Sow[ FactorInteger[n][[1, 1]]]]]][[2, 1]] (* Jean-François Alcover, Sep 02 2016 *) CROSSREFS Sequence in context: A097051 A323761 A078832 * A185049 A186181 A324983 Adjacent sequences:  A086407 A086408 A086409 * A086411 A086412 A086413 KEYWORD nonn,nice AUTHOR Reinhard Zumkeller, Jul 18 2003 STATUS approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)