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.
Index entry for sequences related to LEGO blocks
Cf. A112389, A123762 - A123827, A123829 - A123849.
Sequence in context: A053404 A295794 A122003 * A105796 A226051 A238338
Adjacent sequences: A123824 A123825 A123826 * A123828 A123829 A123830
Søren Eilers, Oct 29 2006