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
KEYWORD
nonn
AUTHOR
Robert Price, Jun 04 2013
STATUS
approved