The odd part of a positive integer is defined by
where is the exponent of the exact power of 2 dividing . is therefore the product of odd factors of . The values for , 2, ..., are 1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 11, ... (OEIS A000265).
More things to try:
Weisstein, Eric W. "Odd Part." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/OddPart.html
of a positive integer 
is defined by
is the exponent of the exact power
of 2 dividing 
.
is therefore the product of odd
factors of 
.
The values for 
,
2, ..., are 1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 11, ... (OEIS A000265).
