An-a(n- 1)=2n, a2-a 1=2 squared, a3-a2=2 cubic. . . . . Left plus left, right plus right, that is, the square of an-a65438 +0 = 2+2 cube ... all the way to the n power of 2; A 1=3 is the zeroth power of 2 plus the first power of 2.

So the zeroth power of an =+the first power of 2+. . . +2 to the power of n = A0(n+65438+ 1-q to the power of 0) /( 1-q), that is, 1(n+65438+ 1-2 to the power of 0)/(/kloc-2)