A069627 Sum_{k=1..n} floor(n*(n-1)/(2*k)).

0, 0, 1, 5, 12, 22, 35, 53, 74, 101, 129, 162, 202, 244, 292, 344, 403, 463, 527, 601, 676, 762, 844, 937, 1035, 1138, 1245, 1355, 1476, 1597, 1726, 1862, 2002, 2149, 2300, 2454, 2621, 2784, 2957, 3136, 3323, 3515, 3707, 3914, 4119, 4338, 4551, 4782, 5012, 5250

Offset: 0

Author

N. J. A. Sloane, Oct 28 2008

Keywords

• nonn

Comments

The old entry with this sequence number was a duplicate of A072137.

Crossrefs

Cf. A006218, A118014.

Programs

Maple

f:=n->add(floor( n*(n-1)/(2*k) ),k=1..n );

Formula

a(n) ~ n^2 * (gamma + log(n))/2, where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Dec 23 2020