A260073 Number of triples {x, y, x mod y} of three distinct divisors of n.

0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 3, 0, 1, 0, 0, 0, 3, 0, 3, 1, 1, 0, 6, 0, 1, 0, 2, 0, 8, 0, 0, 0, 1, 0, 9, 0, 1, 1, 5, 0, 9, 0, 2, 0, 1, 0, 10, 0, 3, 0, 3, 0, 6, 1, 4, 1, 1, 0, 23, 0, 1, 2, 0, 0, 7, 0, 3, 0, 6, 0, 18, 0, 1

Offset

1,12

Comments

a(n) = 0 if n is a prime power. - Charles R Greathouse IV, Aug 20 2015

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

a(6) = 1 because x = 3, y = 2, x mod y = 1 and 3, 2, 1 are distinct divisors of 6.

Prog

(PARI) a(n)=my(d=divisors(n), x, y, z); sum(i=2, #d-2, y=d[i]; sum(j=i+1, #d-1, x=d[j]; z=x%y; z && n%z==0)) \\ Charles R Greathouse IV, Aug 20 2015

Crossrefs

Cf. A027750.

Sequence in context: A111025 A271620 A098018 * A196306 A107093 A051830

Adjacent sequences: A260070 A260071 A260072 * A260074 A260075 A260076

Keyword

nonn

Author

Juri-Stepan Gerasimov, Aug 19 2015

Extensions

Corrected and edited by Charles R Greathouse IV, Aug 20 2015

Status

approved