OFFSET
1,3
FORMULA
a(n) = n^2 * Sum_{i=1..floor((n-1)/2)} (floor((n-i)/i) - floor((n-i-1)/i)).
MATHEMATICA
Table[n^2 * Sum[(Floor[(n - i)/i] - Floor[(n - i - 1)/i]), {i, Floor[(n - 1)/2]}], {n, 80}]
PROG
(Magma) [0, 0] cat [&+[(((n-k) div k)-(n-k-1) div k)*n^2: k in [1..(n-1) div 2]]: n in [3..80]]; // Vincenzo Librandi, May 02 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, May 01 2018
STATUS
approved