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A086410 Smallest prime factor of 3-smooth numbers, with a(1)=1. 6
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
LINKS
FORMULA
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
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
KEYWORD
nonn,nice
AUTHOR
Reinhard Zumkeller, Jul 18 2003
STATUS
approved

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Last modified May 26 23:01 EDT 2024. Contains 372847 sequences. (Running on oeis4.)