Find the sum of odd integers from 1 to 2001.

Explanation

To find the sum of odd integers from 1 to 2001, we can follow these steps:

### Step 1: Identify the sequence of odd integers
The odd integers from 1 to 2001 form an arithmetic progression (AP) with the first term \( a = 1 \) and the common difference \( d = 2 \). The series is:
\[ 1, 3, 5, 7, \ldots, 2001 \]

### Step 2: Determine the number of terms (n)
To find the number of terms in the series, we can use the formula for the \( n \)-th term of an AP:
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