Unsigned Stirling Number of the First Kind of 1

Theorem

 * $\displaystyle \left[{1 \atop n}\right] = \delta_{1 n}$

where:
 * $\displaystyle \left[{1 \atop n}\right]$ denotes an unsigned Stirling number of the first kind
 * $\delta_{1 n}$ is the Kronecker delta.

Also see

 * Signed Stirling Number of the First Kind of 1
 * Stirling Number of the Second Kind of 1