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.

0, 0, 0, 1, 1, 2, 4, 10, 14, 37, 55, 142, 208, 531, 792, 2015, 3029, 7621

Offset

1,6

Comments

This sequence enumerates a subset of the polyominoes enumerated by A056878.

Links

Table of n, a(n) for n=1..18.

Formula

a(n) = A056878(2*n) - A351159(2*n).

Example

a(4)=1 because of:
    O
   OOO
  OOO
   O

Crossrefs

Cf. A000105, A056878, A351159.

Sequence in context: A082230 A236547 A078775 * A056392 A080149 A217134

Adjacent sequences: A351157 A351158 A351159 * A351161 A351162 A351163

Keyword

nonn,more

Author

John Mason, Feb 03 2022

Extensions

a(17)-a(18) from John Mason, Dec 17 2024

Status

approved