A294151 Number of perforated polyominoes with n cells, identifying mirror images.

1, 1, 2, 3, 8, 13, 36, 76, 202, 482, 1281, 3277, 8749, 23083, 62056, 166498, 450576, 1220542, 3321870, 9057388, 24769906

Offset: 1

Author

George Sicherman, Oct 23 2017

Keywords

• nonn
• more
• hard

Comments

A perforated polyomino is a polyomino in which every cell has at least one even coordinate.

Examples

			a(4)=3 because there are 5 tetrominoes, and the skew and square tetrominoes do not lie in the perforated grid, which leaves 3.
		

Crossrefs

Cf. A000105, number of polyominoes with n cells; A292065, number of Besźel Polycubes with n cells, distinguishing mirror images; A292157, same but identifying mirror images.

Extensions

a(16) - a(21) from Joerg Arndt, Dec 11 2023