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A123813
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 8 which is flat, i.e., with all blocks in parallel position, and symmetric after a rotation by 180 degrees.
0
1, 1, 9, 13, 153, 249, 3011, 5209, 63991, 114321, 1421173, 2603433, 32518012, 60650817, 760402013, 1437977218
OFFSET
1,3
CROSSREFS
KEYWORD
nonn
AUTHOR
Søren Eilers, Oct 29 2006
EXTENSIONS
a(11)-a(16) from Søren Eilers, Sep 14 2018
STATUS
approved