If implicit multiplication is not active, something like 4y^2 should raise an error. This is what actually happens:
sage: var("y"); 4y^2
File "<ipython-input-22-25bcbc82148c>", line 1
var("y"); 4y**Integer(2)
^
SyntaxError: invalid syntax
If we replace y by a different variable or consider a similar expression, we also get an error... except if the variable is r or R. For example,
sage: var("r, R"); 4r^2, 3R + 5r + 2R^3
(16, 16)
Surprisingly, there is no error. Variables r and R seem to be gobbled, so that SageMath parses 4r^2 as 4**Integer(2) and 3R + 5r + 2R^3 as 3 + 5 + 2**Integer(3). Why?
