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%I #13 Feb 05 2022 03:11:39
%S 0,0,0,1,1,2,4,10,14,37,55,142,208,531,792,2015
%N 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.
%C This sequence enumerates a subset of the polyominoes enumerated by A056878.
%F a(n) = A056878(2*n) - A351159(2*n).
%e a(4)=1 because of:
%e O
%e OOO
%e OOO
%e O
%Y Cf. A000105, A056878, A351159.
%K nonn,more
%O 1,6
%A _John Mason_, Feb 03 2022
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