A352078 Number of ordered triples (a,b,c) of positive integers less than n with the property that n divides a*b*c.

0, 0, 0, 7, 0, 42, 0, 87, 80, 156, 0, 439, 0, 342, 528, 687, 0, 1160, 0, 1543, 1152, 930, 0, 3207, 1024, 1332, 2024, 3319, 0, 5502, 0, 4447, 3120, 2352, 4176, 9287, 0, 2970, 4464, 10935, 0, 11724, 0, 8887, 12176, 4422, 0, 19983, 4752, 12424, 7872, 12679, 0, 20330, 11280, 23271, 9936

Offset

1,4

Comments

a(n) = 0 iff n is prime or 1.

Links

Table of n, a(n) for n=1..57.

Example

For n = 4 the ordered triples are (1,2,2), (2,1,2), (2,2,1), (2,2,2), (2,2,3), (2,3,2), (3,2,2).

Mathematica

Table[Dimensions[Solve[a*b*c == 0 && a != 0 && b != 0 && c != 0, {a, b, c}, Modulus -> n]][[1]], {n, 2, 100}]

Crossrefs

Cf. A268631.

Sequence in context: A157779 A222322 A228762 * A046273 A167317 A266436

Adjacent sequences: A352075 A352076 A352077 * A352079 A352080 A352081

Keyword

nonn

Author

Luca Onnis, Mar 28 2022

Status

approved