Problem in creating a vector

[termo]

I need to create a vector A_vec. The code line is:

self.A_vec = [self.B[0:j], self.B[j] + self.C / self.D, self.B[j+1:len(self.E)]]

and the error is: "unsupported operand type(s) for -: 'float' and 'list'"

I think the problem are the expression as

 self.B[0:j] 

but I don't know how to solve it.
The meaning of that expression is to take values from

 self.B[0] 

to

 self.B[j] 

where j is a int number es 2.
I tried also with

 self.B[range(0,j)] 

but it doesn't work.