

A123793


Number of ways to build a contiguous building with n LEGO blocks of size 1 X 5 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.


0



1, 3, 5, 18, 42, 170, 405, 1769, 4507, 20081, 53008, 240428, 652160, 3002052, 8299727, 38570944, 108387118, 507729121, 1444491686, 6809942459
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