OFFSET
1,4
COMMENTS
A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793.
EXAMPLE
The nontrivial divisors of 18 are {2, 3, 6, 9}, so a(18) = 2^1 + 2^2 + 2^5 + 2^8 = 294.
MATHEMATICA
Table[Total[(2^DeleteCases[Divisors[n], 1|n])/2], {n, 100}]
PROG
(Python)
from sympy import divisors
def A328337(n): return sum(1<<(d-1) for d in divisors(n, generator=True) if 1<d<n) # Chai Wah Wu, Jul 15 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 15 2019
STATUS
approved