# Sequences

Discrete Mathematics Level pending

Let $$\{a_1,a_2,a_3,a_4,a_5\ldots a_n\}$$ be a sequence such that $$a_1=2$$ and $$a_n-a_{n-1}=2n$$ for all $$n>1$$.

Then let $$Z=a_1+a_2+a_3+\ldots a_{20}$$ .

What is the sum of digits of $$Z$$?

Note:

• For no confusion, the sum of the digits in 99929 is 38. The sum of the digits in 1000 is 1.
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