A056548 a(n) = Sum_{k>=1} round(n/k) where round(1/2) = 0.

0, 1, 4, 7, 11, 15, 19, 23, 29, 32, 37, 43, 47, 52, 58, 62, 68, 73, 79, 84, 90, 94, 100, 108, 112, 117, 124, 128, 136, 142, 146, 152, 160, 165, 171, 177, 183, 188, 196, 202, 208, 215, 219, 227, 233, 237, 247, 253, 259, 263, 272, 277, 283, 293, 297, 303, 311, 315

Offset: 0

Author

Henry Bottomley, Jun 21 2000

Keywords

• easy
• nonn

Crossrefs

Cf. A000005, A001227, A006218, A056549.

Formula

a(n) = A056549(n) - A001227(n).

Conjecture: a(n) = Sum_{k=n..2n-1} d(k), where d is the number of divisors function (A000005). - Ridouane Oudra, Apr 29 2019