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A351160
Number of polyominoes of 2n cells with both diagonal symmetries, for which the 180-degree rotational symmetry has an axis that coincides with a vertex of a square, but without 90-degree rotational symmetry.
2
0, 0, 0, 1, 1, 2, 4, 10, 14, 37, 55, 142, 208, 531, 792, 2015
OFFSET
1,6
COMMENTS
This sequence enumerates a subset of the polyominoes enumerated by A056878.
FORMULA
a(n) = A056878(2*n) - A351159(2*n).
EXAMPLE
a(4)=1 because of:
O
OOO
OOO
O
CROSSREFS
KEYWORD
nonn,more
AUTHOR
John Mason, Feb 03 2022
STATUS
approved