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A122179
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Number of ways to write n as n = x*y*z with 1<x<=y<=z<n.
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2
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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; internal format)
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OFFSET
| 1,24
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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.
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EXAMPLE
| a(24) = 2 because 24 = 2*2*6 = 2*3*4, two products of three proper factors of 24.
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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, ", "))
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CROSSREFS
| Cf. A034836, A033942, A037143, A088432, A088433, A088434, A122180.
Sequence in context: A128582 A101606 A125005 * A125203 A023565 A025922
Adjacent sequences: A122176 A122177 A122178 * A122180 A122181 A122182
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KEYWORD
| nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 23 2006
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