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A088432 Number of ways to write n as n = u*v*w with 1 <= u < v <= w. 6
0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 0, 1, 1, 2, 0, 3, 0, 2, 1, 1, 0, 4, 1, 1, 1, 2, 0, 4, 0, 3, 1, 1, 1, 5, 0, 1, 1, 4, 0, 4, 0, 2, 2, 1, 0, 7, 1, 3, 1, 2, 0, 4, 1, 4, 1, 1, 0, 8, 0, 1, 2, 4, 1, 4, 0, 2, 1, 4, 0, 9, 0, 1, 3, 2, 1, 4, 0, 6, 2, 1, 0, 8, 1, 1, 1, 4, 0, 8, 1, 2, 1, 1, 1, 9, 0, 3, 2, 6, 0, 4, 0, 4, 4, 1, 0, 9, 0, 4, 1, 6, 0, 4, 1, 2, 2, 1, 1, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,12

COMMENTS

a(n)=0 iff n=1 or n is prime: a(A008578(n)) = 0, a(A002808(n)) > 0.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..3003

EXAMPLE

n=12: (1,2,6), (1,3,4): therefore a(12)=2;

n=18: (1,2,9), (1,3,6), (2,3,3): therefore a(18)=3.

PROG

(PARI) A088432(n) = { my(s=0); fordiv(n, u, for(v=u+1, n-1, for(w=v, n, if(u*v*w==n, s++)))); (s); }; \\ Antti Karttunen, Aug 24 2017

CROSSREFS

Cf. A034836, A088433, A088434, A122179, A122180.

Sequence in context: A202177 A029360 A185279 * A304455 A238951 A071466

Adjacent sequences:  A088429 A088430 A088431 * A088433 A088434 A088435

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 01 2003

EXTENSIONS

Data section extended to 120 terms by Antti Karttunen, Aug 24 2017

STATUS

approved

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Last modified April 19 06:59 EDT 2019. Contains 322237 sequences. (Running on oeis4.)