0,2,5,9,14. The expression of the nth number It is easy to see from the sequence that the sequence is + 2; + 3; + 4; + 5 But how can I not find the general formula? want

0,2,5,9,14. The expression of the nth number It is easy to see from the sequence that the sequence is + 2; + 3; + 4; + 5 But how can I not find the general formula? want

The first item is 0
2 is 0 + 2
Then 0 + 2 + 3
Then 0 + 2 + 3 + 4
See what? It's just an arithmetic sequence
(2 + n) (n-1) / 2 = n square - 2 + n / 2

Elden Ring Premiere

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