an = a1 14^n-1a1 = 3a5=？

To find a[5], we first need to use the formula given to find a[1], a[2], a[3], and a[4]:

a[1] = 3 a[2] = a[1] * 14^(2-1) = 3 * 14 = 42 a[3] = a[1] * 14^(3-1) = 3 * 196 = 588 a[4] = a[1] * 14^(4-1) = 3 * 2744 = 8232

Now that we have found the first four terms, we can use the formula to find a[5]:

a[5] = a[1] * 14^(5-1) = 3 * 38416 = 115248

Therefore, a[5] = 115248.