The given sequence is 11, 15, 19, 23, 27, ..., which is an arithmetic sequence.
To find the sum of the first 23 terms, we first identify the first term (\(a\)) and the common difference (\(d\)) of the sequence.
The first term is: \[ a = 11 \]
The common difference can be calculated as: \[ d = 15 - 11 = 4 \]
The formula for the sum of the first \(n\) terms of an arithmetic series is given by: \[ S_n = \frac{n}{2} \times (2a + (n-1)d) \]
In this case, \(n = 23\). Now, we substitute \(n\), \(a\), and \(d\) into the formula: \[ S_{23} = \frac{23}{2} \times (2 \times 11 + (23-1) \times 4) \]
Calculating \(2a\): \[ 2a = 2 \times 11 = 22 \]
Calculating \((n-1)d\): \[ (n-1)d = (23-1) \times 4 = 22 \times 4 = 88 \]
Now we can substitute these values back into the sum formula: \[ S_{23} = \frac{23}{2} \times (22 + 88) \]
Calculating \(22 + 88\): \[ 22 + 88 = 110 \]
Putting it all together: \[ S_{23} = \frac{23}{2} \times 110 \]
Calculating \(\frac{23 \times 110}{2}\): \[ 23 \times 110 = 2530 \] \[ S_{23} = \frac{2530}{2} = 1265 \]
Thus, the sum of the first 23 terms of the sequence is: \[ \boxed{1265} \]