Find the first 4 terms of the recursively defined sequence a

Find the first 4 terms of the recursively defined sequence. a1=3, a2=3, a Subscript n+1=a Subscript n+a Subscript n1

Solution

a₁ = 3,

a₂ = 3

a_n+1 = a_n + a_n-1

a3 = a2 + a1 = 3 + 3 = 6

a4 = a3 + a2 = 6 + 3 = 9

a5 = a4 + a3 = 9 + 6 = 15

a6 = a5 + a4 = 15 + 9 = 24