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A258570
Smallest prime factors of 5-full numbers, a(1)=1.
6
1, 2, 2, 2, 3, 2, 2, 3, 2, 2, 3, 5, 2, 3, 2, 2, 2, 5, 2, 7, 3, 2, 2, 2, 2, 3, 2, 2, 2, 5, 2, 2, 7, 2, 2, 2, 11, 3, 2, 2, 2, 2, 2, 2, 13, 2, 5, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 7, 2, 2, 2, 2, 2, 2, 2, 17, 2, 3, 2, 2, 11, 2, 5, 2, 2, 2, 2, 2, 3, 19, 2, 2, 2
OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 (some terms corrected by Andrew Howroyd)
FORMULA
a(n) = A020639(A069492(n)).
a(A258602(n)) = A000040(n) and a(m) != A000040(n) for m < A258602(n).
PROG
(Haskell)
a258570 = a020639 . a069492
(PARI) lista(kmax) = {my(f); print1(1, ", "); for(k = 2, kmax, f = factor(k); if(vecmin(f[, 2]) > 4, print1(f[1, 1], ", "))); } \\ Amiram Eldar, Sep 12 2024
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jun 06 2015
STATUS
approved