A123779 - OEIS

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A123779

Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x4 which is symmetric after a rotation by 180 degrees.

%I #5 Oct 09 2013 14:20:52

%S 1,1,21,67,849,3185,39868,162562,2027829

%N Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x4 which is symmetric after a rotation by 180 degrees.

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

%K nonn

%O 1,3

%A _Søren Eilers_, Oct 29 2006