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 A028422 Number of ways n can be properly factored. 27
 0, 0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 3, 0, 1, 1, 4, 0, 3, 0, 3, 1, 1, 0, 6, 1, 1, 2, 3, 0, 4, 0, 6, 1, 1, 1, 8, 0, 1, 1, 6, 0, 4, 0, 3, 3, 1, 0, 11, 1, 3, 1, 3, 0, 6, 1, 6, 1, 1, 0, 10, 0, 1, 3, 10, 1, 4, 0, 3, 1, 4, 0, 15, 0, 1, 3, 3, 1, 4, 0, 11, 4, 1, 0, 10, 1, 1, 1, 6, 0, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,8 COMMENTS a(n) = A066032(n,n-1) for n > 1; also number of ways to write n as a product with all factors <= n/2. - Reinhard Zumkeller, Oct 01 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE 12 can be expressed as 2*6, 3*4 or 2*2*3, so a(12)=3. PROG (Haskell) a028422 1 = 0 a028422 n = (map (last . init) a066032_tabl) !! (n-1) -- Reinhard Zumkeller, Oct 01 2012 CROSSREFS A001055(n) - 1. Cf. A216599, A216600, A216601, A216602. Sequence in context: A337345 A294904 A055212 * A064577 A322435 A113949 Adjacent sequences:  A028419 A028420 A028421 * A028423 A028424 A028425 KEYWORD nonn AUTHOR Glen Burch (gburch(AT)erols.com) STATUS approved

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Last modified September 26 11:29 EDT 2020. Contains 337367 sequences. (Running on oeis4.)