1,2,5,10,17 I know the answer!

1,2,5,10,17,26,… The difference of two adjacent terms is 1, 3, 5, 7, 9 So A1 = 1 a2-a1 = 1 = 2-1 a3-a2 = 3 = 2 × 2-1 So, an = 1 + 1 + 3 + 5 + 7 + 9 + + (2n-3) = (n-1) ^ 2 + 1 or notice: A1

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