Ramus's Identity/Examples

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Examples of Ramus's Identity

Example: $k = 1, m = 3$

\(\ds \sum_{j \mathop \ge 0} \binom n {3 j + 1}\) \(=\) \(\ds \binom n 1 + \binom n 4 + \binom n 7 + \cdots\)
\(\ds \) \(=\) \(\ds \frac 1 3 \paren {2^n + 2 \cos \frac {\paren {n - 2} \pi} 3}\)