Definition:Sigma Function/Sequence

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Definition

The sequence of values of the sigma function for the first few positive integers begins:

$\begin{array} {r|r} n & \sigma \left({n}\right) \\ \hline 1 & 1 \\ 2 & 3 \\ 3 & 4 \\ 4 & 7 \\ 5 & 6 \\ 6 & 12 \\ 7 & 8 \\ 8 & 15 \\ 9 & 13 \\ 10 & 18 \\ 11 & 12 \\ 12 & 28 \\ 13 & 14 \\ 14 & 24 \\ 15 & 24 \\ 16 & 31 \end{array}$

This sequence is A000203 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).


Sources