6. Recursively Defined Sequences
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Look for a pattern in the difference of the consecutive terms.
a_1=3, a_n=a_(n-1)+2^n
We see that each difference is a power of 2. Consider the difference between the fourth and the third term, 2 and 4. a_4=a_3+2^4 ⇔ a_4=a_(4-1)+2^4 We can write the recursive equation. a_n=a_(n-1)+2^n The first term and the recursive equation gives us the recursive rule. Recursive Rule: a_1=3, a_n=a_(n-1)+2^n