What kind of sequence/progression is this? What will be the answer to the question?

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There are 20 urns such that the first urn contains 5 balls, the second contains 10 balls and in general the $k^{th}$ urn contains $2k + 1$ balls more that that in $(k - 1)^{th}$ urn. Then what is the total number of balls in all the urns?

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The $n$-th term of the sequence is $n^2+2n+2.$ Hence the total number of balls in the urns is $$\sum\limits_{n=1}^{20} (n^2+2n+2)=3330.$$