Answer
0, 0, 2, 2
Work Step by Step
The first four terms of the sequence $e_n = \left \lfloor{n/2}\right \rfloor * 2$ are
$e_n = \left \lfloor{0/2}\right \rfloor * 2 = 0 * 2$
$e_n = \left \lfloor{1/2}\right \rfloor * 2 = 0 * 2$
$e_n = \left \lfloor{2/2}\right \rfloor * 2 = 1 * 2$
$e_n = \left \lfloor{3/2}\right \rfloor * 2 = 1 * 2$