In a sequence of positive numbers, each term after the first two terms is the sum of all of the previous terms. If the first term is $a$, the second term is 2 , and the sixth term is 56, then the value of $a$ is
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
Using the rules for forming the sequence, the third term is $a+2$ and the fourth term is

$a+2+(a+2)=2(a+2)$. Similarly, the fifth term is $4(a+2)$ and the sixth term is $8(a+2)$. But the sixth term is 56 , so $8(a+2)=56$ or $a+2=7$ or $a=5$.

ANSWER: (E)