STATUS
proposed
approved
proposed
approved
editing
proposed
(Python)
from math import isqrt
def A143128(n): return ((-((s:=isqrt(n))*(s+1))**2*(2*s+1)>>1) + sum((q:=n//k)*(q+1)*k*(3*k+2*q+1) for k in range(1, s+1)))//6 # Chai Wah Wu, Oct 21 2023
approved
editing
reviewed
approved
proposed
reviewed
editing
proposed
(Python)
def A143128(n): return sum(k**2*(m:=n//k)*(m+1)>>1 for k in range(1, n+1)) # Chai Wah Wu, Oct 20 2023
approved
editing
(MAGMAMagma) [(&+[k*DivisorSigma(1, k): k in [1..n]]): n in [1..50]]; // G. C. Greubel, Nov 21 2018
reviewed
approved
proposed
reviewed