A152967 Partial sums of A152770.

0, 0, 0, 1, 1, 4, 4, 8, 10, 15, 15, 26, 26, 33, 39, 50, 50, 66, 66, 83, 91, 102, 102, 131, 135, 148, 158, 181, 181, 216, 216, 242, 254, 271, 281, 328, 328, 347, 361, 404, 404, 451, 451, 486, 514, 537, 537, 604, 610, 648, 666, 707, 707, 766, 780, 837, 857, 886, 886, 983, 983

Offset: 1

Author

Omar E. Pol, Dec 22 2008

Keywords

• easy
• nonn

Links

• B. D. Swan, Table of n, a(n) for n=1..10000

Crossrefs

Cf. A152770.

Programs

Mathematica

Accumulate[Array[DivisorSigma[1,#]-DivisorSigma[0,#]-#+1&,70]] (* Harvey P. Dale, Dec 27 2011 *)

Formula

a(n) = Sum_{i=1..n} (i-1)*floor((n-i)/i). - Wesley Ivan Hurt, Sep 13 2017