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A294151
Number of perforated polyominoes with n cells, identifying mirror images.
1
1, 1, 2, 3, 8, 13, 36, 76, 202, 482, 1281, 3277, 8749, 23083, 62056, 166498, 450576, 1220542, 3321870, 9057388, 24769906
OFFSET
1,3
COMMENTS
A perforated polyomino is a polyomino in which every cell has at least one even coordinate.
EXAMPLE
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.
Sequence in context: A374301 A151889 A366020 * A294566 A129873 A025575
KEYWORD
nonn,more,hard
AUTHOR
George Sicherman, Oct 23 2017
EXTENSIONS
a(16) - a(21) from Joerg Arndt, Dec 11 2023
STATUS
approved