OFFSET
1,4
COMMENTS
FORMULA
a(n) = A034729(n) - 2^(n-1). - Michel Marcus, Nov 22 2014
MATHEMATICA
With[{n=Range[100]}, (1/2) ((Total/@(2^Divisors[n])) - 2^n)]
PROG
(PARI) a(n) = sumdiv(n, k, 2^(k-1)) - 2^(n-1); \\ Michel Marcus, Nov 25 2014
(Python)
from sympy import divisors
def A247146(n): return sum(1<<d-1 for d in divisors(n, generator=True) if d<n) # Chai Wah Wu, Jul 15 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Morgan L. Owens, Nov 21 2014
STATUS
approved