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

Offset: 1

Author

Rick L. Shepherd, Aug 23 2006

Keywords

• nonn

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.

Examples

			a(24) = 2 because 24 = 2*2*6 = 2*3*4, two products of three proper factors of 24.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..8192 (terms 1..2048 from Antti Karttunen)

Crossrefs

Cf. A034836, A033942, A037143, A088432, A088433, A088434, A122180.

Programs

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)&&(xAntti Karttunen, Aug 24 2017