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 A086412 Number of distinct prime factors of 3-smooth numbers. 4
 0, 1, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A001221(A003586(n)); a(n) <= 2. MATHEMATICA s = {}; m = 12; Do[n = 3^k; While[n <= 3^m, AppendTo[s, n]; n*=2], {k, 0, m}]; PrimeNu /@ Union[s] (* Amiram Eldar, Jan 29 2020 *) CROSSREFS Cf. A001221, A003586, A069352, A086414. Sequence in context: A078703 A090629 A248623 * A192006 A006928 A087890 Adjacent sequences: A086409 A086410 A086411 * A086413 A086414 A086415 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jul 18 2003 STATUS approved

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Last modified June 14 13:49 EDT 2024. Contains 373400 sequences. (Running on oeis4.)