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..10.
Index entry for sequences related to LEGO blocks
Cf. A112389, A123762 - A123827, A123829 - A123849.
Sequence in context: A173776 A289909 A000324 * A124421 A262918 A283918
Adjacent sequences: A123814 A123815 A123816 * A123818 A123819 A123820
Søren Eilers, Oct 29 2006