Elementary combinatorics: Arithmetic and geometric sequences
Arithmetic sequences
Write the following sum belonging to an arithmetic sequence \[6+9+12+\cdots + 42\] in sigma notation with summation index \(k\) and calculate it
| \(6+9+12+\cdots + 39+ 42 = {}\) |
| \(6+9+12+\cdots + 39+42 = {}\) |
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