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 A122179 Number of ways to write n as n = x*y*z with 1
 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 1, 1, 0, 1, 0, 2, 0, 0, 0, 3, 0, 0, 0, 2, 0, 1, 0, 1, 1, 0, 0, 4, 0, 1, 0, 1, 0, 2, 0, 2, 0, 0, 0, 4, 0, 0, 1, 3, 0, 1, 0, 1, 0, 1, 0, 6, 0, 0, 1, 1, 0, 1, 0, 4, 1, 0, 0, 4, 0, 0, 0, 2, 0, 4, 0, 1, 0, 0, 0, 6, 0, 1, 1, 3, 0, 1, 0, 2, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,24 COMMENTS x,y,z are proper factors of n. a(n) > 0 iff n is a term of A033942; a(n) = 0 iff n is a term of A037143. LINKS Seiichi Manyama, Table of n, a(n) for n = 1..8192 (terms 1..2048 from Antti Karttunen) EXAMPLE a(24) = 2 because 24 = 2*2*6 = 2*3*4, two products of three proper factors of 24. PROG (PARI) for(n=1, 105, t=0; for(x=2, n-1, for(y=x, n-1, for(z=y, n-1, if(x*y*z==n, t++)))); print1(t, ", ")) (PARI) A122179(n) = { my(s=0); fordiv(n, x, if((x>1)&&(x

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Last modified April 13 18:46 EDT 2021. Contains 342939 sequences. (Running on oeis4.)