Forget math on Wikipedia. After looking at the table that you contacted, you can see the template:
EV Lux
-1 1.25
-0.5 1.75
0 2.50
0.5 3.50
1 5.00
1.5 7.00
2 10.00
2.5 14.00
3 20.00
3.5 28.00
4 40.00
...
1 EV - 5 lux. 2 EV - 10 lux. 3 EV - 20 lux. So it looks logarithmic:
lux = (2 ^ ev) * 2.5;
(2 to EV power, times 2.5)
C-type:
#include <math.h> double evToLux(double ev) { return pow(2, ev) * 2.5; }
Update
Wikipedia has the following formula: 
Update 2
It is important to note that EV is dependent on film speed (ISO). All of the above is true only for ISO 100. It is easy to convert to other speeds: EV(at ISO 100) == EV(at ISO 200) - 1
(H / T Nikolay Rukh)