

A123831


Number of ways to build a contiguous building with n LEGO blocks of size 2 X 4 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.


0




OFFSET

1,1


COMMENTS

The base block is not counted among the n and must be the only block in the bottom layer of the building.


LINKS



CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



