A099738 a(n) = 2*Sum_{k=1..n} (n+1-k) (Sum_{j|k} 1/floor(n/j)).

2, 5, 10, 15, 24, 30, 43, 52, 66, 78, 99, 107, 132, 150, 171, 188, 221, 236, 273, 291, 322, 352, 397, 409, 453, 489, 530, 558, 615, 633, 694, 727, 778, 826, 883, 900, 973, 1027, 1088, 1118, 1199, 1229, 1314, 1362, 1419, 1485, 1578, 1598, 1688, 1745, 1826, 1884

Offset: 1

Author

Leroy Quet, Nov 09 2004

Keywords

• nonn

Comments

Sequence consists entirely of integers.

First differences give A033885.

Programs

Mathematica

f[n_] := 2Sum[(n + 1 - k)*Plus @@ (1/Floor[n/Divisors[k]]), {k, n}]; Table[ f[n], {n, 52}] (* Robert G. Wilson v, Nov 12 2004 *)

Extensions

More terms from Robert G. Wilson v, Nov 12 2004