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%I #17 Apr 15 2023 05:09:24
%S 0,0,0,0,1,0,4,0,19,1,73,4,283,25,1090,106,4183,463,16105,1892,62170,
%T 7752,240907,31212,936447,125609,3651618,503165,14277519,2014826,
%U 55961118,8058790,219813564,32231897,865091976,128897247,3410498446,515554767,13466262587,2062445063,53245595410,8252868076,210800433323
%N Number of free polyominoes with n squares, having 180-degree rotational symmetry about the center of a square, and no other symmetry.
%C The sequence enumerates a subset of the polyominoes enumerated by A006747.
%H John Mason, <a href="/A351615/b351615.txt">Table of n, a(n) for n = 1..50</a>
%e a(5)=1 because of:
%e OO
%e O
%e OO
%Y Cf. A006747, A234008, A351616.
%K nonn
%O 1,7
%A _John Mason_, Feb 15 2022
%E More terms from _John Mason_, Apr 15 2023
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