OFFSET
1,1
COMMENTS
Partial sums of the sum of the divisors of the nonzero multiples of 6.
FORMULA
a(n) = (55*Pi^2/72) * n^2 + O(n*log(n)). - Amiram Eldar, Sep 07 2023
MATHEMATICA
Accumulate[Table[DivisorSigma[1, 6*n], {n, 1, 50}]] (* Amiram Eldar, Sep 07 2023 *)
PROG
(Python)
from math import prod
from collections import Counter
from sympy import factorint
def A365446(n): return sum(prod((p**(e+1)-1)//(p-1) for p, e in (Counter(factorint(m))+Counter([2, 3])).items()) for m in range(1, n+1)) # Chai Wah Wu, Sep 07 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, Sep 04 2023
STATUS
approved