I would very much like to find a formula for this - N. J. A. Sloane.
Table of n, a(n) for n=2..9.
Sequence in context: A186651 A292034 A108982 * A000708 A027248 A192481
Adjacent sequences: A059721 A059722 A059723 * A059725 A059726 A059727
N. J. A. Sloane, Feb 09 2001