A general term formula for sequence 13 + 2,13 + 6,13 + 12,13 + 20,13 + 30?

A general term formula for sequence 13 + 2,13 + 6,13 + 12,13 + 20,13 + 30?

A1 = 2A2 = 2 + 4 = 2 * 3a3 = 2 + 4 + 6 = 3 * 4a4 = 2 + 4 + 6 + 8 = 4 * 5a5 = 2 + 4 + 6 + 8 + 10 = 5 * 6. An = 2 + 4 + 6 + 8 + 10 +... + 2n = 2 (1 + 2 + 3 + 4 + 5 +... + n) = n (n + 1) | an = n (n + 1) + 13. This is my conclusion after meditation. If you can't ask, I will try my best to solve it for you