The function defined by
See also G-Function, Glaisher-Kinkelin Constant, K-Function
References
Sloane, N. J. A. Sequence
A002109/M3706
in ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.
The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.