OFFSET
1,3
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..500
FORMULA
a(n) << n^(2+e) for all e > 0. - Charles R Greathouse IV, Jun 17 2013
MATHEMATICA
a[n_] := Sum[Sum[Sum[Boole[d <= n && d > 1 && b*c/d <= n && b*c > d], {d, Divisors[b*c]}], {c, 2, n}], {b, 2, n}];
Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Apr 25 2024, after Charles R Greathouse IV *)
PROG
(PARI) a(n)=sum(b=2, n, sum(c=2, n, sumdiv(b*c, a, a<=n && a>1 && b*c/a<=n && b*c>a))) \\ Charles R Greathouse IV, Jun 17 2013
CROSSREFS
KEYWORD
nice,nonn
AUTHOR
Graziano Aglietti (mg5055(AT)mclink.it), Feb 04 2008
STATUS
approved