An orthoplex polyominoes does not extend more than two units along any axis.
Table of n, a(n) for n=1..10.
There are a(5)=5 orthoplex pentominoes: the two 3-D pentominoes that fit in a 2 X 2 X 2 box and the three 4-D pentominoes.
A005519 is a superset.
Sequence in context: A006483 A177960 A271659 * A097144 A219108 A176964
Adjacent sequences: A049537 A049538 A049539 * A049541 A049542 A049543
Robert A. Russell