The base block is not counted among the n and must be the only block in the bottom layer of the building.
Table of n, a(n) for n=1..9.
Cf. A112389, A123762 - A123827, A123829 - A123849.
Sequence in context: A083177 A110466 A110383 * A163288 A092806 A138485
Adjacent sequences: A123780 A123781 A123782 * A123784 A123785 A123786
Søren Eilers, Oct 29 2006