Tilings related by a symmetry of the polyomino that is not a symmetry of the tiling count as distinct (thus, the square tetromino counts as being tiled in two distinct ways).
Table of n, a(n) for n=1..9.
Cf. A056785, A056786, A213376, A213377.
Sequence in context: A159249 A087544 A305667 * A189356 A155672 A073844
Adjacent sequences: A213375 A213376 A213377 * A213379 A213380 A213381
Joseph Myers, Jun 10 2012