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

Author

Gary W. Adamson, Aug 03 2008

Keywords

• nonn

Examples

			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).
		

Crossrefs

Cf. A000005, A006218, A143273.

Programs

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

Formula

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

Extensions

More terms from Eric M. Schmidt, Feb 28 2014