Fifteen integers a1,a2,a3,⋯ ,a15a_1, a_2, a_3, \cdots, a_{15} are arranged in order on a number line. The integers are equally spaced and have the property that 1≤a1≤10,13≤a2≤20,241≤a15≤2501 \le a_1 \le 10, 13 \le a_2 \le 20, 241 \le a_{15} \le 250 What is the sum of digits of a14a_{14}?
A. 8
B. 9
C. 10
D. 11
E. 12

Arithmetic sequences and Gauss summation中文
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A. 8

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