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Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 2 which is symmetric after a rotation by 90 degrees.
0

%I #6 Oct 09 2013 14:20:53

%S 1,1,1,1,3,4,5,10,26,38,51,121,324,488,673,1808

%N Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 2 which is symmetric after a rotation by 90 degrees.

%Y Cf. A112389, A123762 - A123827, A123829 - A123849.

%K nonn

%O 1,5

%A _Søren Eilers_, Oct 29 2006