A226359 Number of ordered triples (i,j,k) with |i|, |j|, |k|, |i*j*k| <= n.

1, 27, 93, 183, 321, 459, 669, 855, 1121, 1379, 1685, 1967, 2393, 2723, 3125, 3551, 4049, 4475, 5045, 5519, 6137, 6707, 7301, 7871, 8681, 9323, 10013, 10735, 11545, 12259, 13189, 13951, 14881, 15739, 16621, 17527, 18673, 19579, 20557, 21559, 22753, 23755

Offset

0,2

Links

Robert Price and Charles R Greathouse IV, Table of n, a(n) for n = 0..10000 (terms through 100 from Robert Price)

Mathematica

f[n_]:=Length[Complement[Union[Flatten[Table[If[Abs[i*j*k] <=  n, {i, j, k}], {i, -n, n}, {j, -n, n}, {k, -n, n}], 2]], {Null}]]; Table[f[n], {n, 0, 100}]

Prog

(PARI) a(n)=12*n^2+6*n+1+8*sum(i=1, n, n\i*numdiv(i)) \\ Charles R Greathouse IV, Jun 04 2013

Crossrefs

Cf. A100450, A226357.

Sequence in context: A228600 A286192 A101100 * A078183 A072252 A154041

Adjacent sequences: A226356 A226357 A226358 * A226360 A226361 A226362

Keyword

nonn

Author

Robert Price, Jun 04 2013

Status

approved