concatenate

[mcgrim]

I am trying to concatenate 2 lists (L3 and L4) but L5 does not print any output.
How come?

L=[1,2]
L3=3*L

L4=[k**2 for k in L3]


L5 = L3 + L4 
print(L3)
print(L4)
list(L5)