Question 881622
Do you mean An=A(n-1) + A(n-2)?
 
A4=A3+A2=4
A6=A5+A4=6
A5+4=6
A5=2
so we have 
A4=4
A5=2
A6=6
A7=8
A8=14
A9=22
A10=36
A11=48
A12=84

That is not an arithmetic sequence.