A143274 a(n) = n * A006218(n).

1, 6, 15, 32, 50, 84, 112, 160, 207, 270, 319, 420, 481, 574, 675, 800, 884, 1044, 1140, 1320, 1470, 1628, 1748, 2016, 2175, 2366, 2565, 2828, 2987, 3330, 3503, 3808, 4059, 4318, 4585, 5040, 5254, 5548, 5850, 6320, 6560, 7056, 7310, 7744, 8190, 8556, 8836

Offset

1,2

Links

Table of n, a(n) for n=1..47.

Formula

a(n) = n * A006218(n), where A006218(n) = partial sums of d(n). Equals row sums of triangle A143273.

Example

a(4) = 32 = 4 * A006218(4), where A006218 = (1, 3, 5, 8, 10,...).
a(4) = 32 = sum of row 4 terms of triangle A143273: (4 + 8 + 8 + 12).

Prog

(PARI) a(n) = n*sum(k=1, n, n\k); \\ Michel Marcus, Mar 19 2016
(Python)
from math import isqrt
def A143274(n): return (-(s:=isqrt(n))**2+(sum(n//k for k in range(1, s+1))<<1))*n # Chai Wah Wu, Oct 23 2023

Crossrefs

Cf. A000005, A006218, A143273.

Sequence in context: A134506 A273117 A273689 * A273332 A273427 A273764

Adjacent sequences: A143271 A143272 A143273 * A143275 A143276 A143277

Keyword

nonn

Author

Gary W. Adamson, Aug 03 2008

Extensions

More terms from Eric M. Schmidt, Feb 28 2014

Status

approved