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Smallest prime factors of 6-full numbers, a(1)=1.
6

%I #14 Sep 12 2024 01:43:41

%S 1,2,2,2,2,3,2,2,3,2,3,2,5,2,3,2,2,3,2,5,2,7,2,2,3,2,2,2,2,5,2,2,3,2,

%T 2,7,2,2,2,2,2,2,3,2,11,5,2,2,2,2,2,2,2,2,2,2,3,13,2,2,7,2,2,2,2,2,2,

%U 2,5,2,2,2,3,2,2,3,2,2,2,2,2,11,2,2,2

%N Smallest prime factors of 6-full numbers, a(1)=1.

%H Andrew Howroyd, <a href="/A258571/b258571.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..191 from Reinhard Zumkeller)

%F a(n) = A020639(A069493(n)).

%F a(A258603(n)) = A000040(n) and a(m) != A000040(n) for m < A258603(n).

%o (Haskell)

%o a258571 = a020639 . a069493

%o (PARI) lista(kmax) = {my(f); print1(1, ", "); for(k = 2, kmax, f = factor(k); if(vecmin(f[, 2]) > 5, print1(f[1, 1], ", "))); } \\ _Amiram Eldar_, Sep 12 2024

%Y Cf. A069493, A020639, A258603, A258567, A258568, A258569, A258570.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Jun 06 2015