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%I A351159 #12 Feb 05 2022 03:11:08
%S A351159 0,0,0,0,0,0,1,0,0,0,2,1,3,1,6,4,9,6,20,19,32,25,64,82,114,107,217,
%T A351159 332,397,442,751,1316
%N A351159 Number of polyominoes of n cells with both diagonal symmetries, for which the 180-degree rotational symmetry has an axis that coincides with the center of a square, but without 90-degree rotational symmetry.
%C A351159 This sequence enumerates a subset of the polyominoes enumerated by A056878.
%F A351159 For odd n, a(n) = A056878(n); for even n, a(n) = A056878(n) - A351160(n/2).
%e A351159 For a(7)=1, the heptomino with exactly fourfold symmetry and axes of symmetry parallel to the diagonals of the cells is composed of two 2 X 2 squares with one cell in common.
%Y A351159 Cf. A000105, A056878, A351160.
%K A351159 nonn,more
%O A351159 1,11
%A A351159 _John Mason_, Feb 03 2022

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