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A123797
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 6 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.
0
1, 1, 7, 10, 88, 142, 1277, 2193, 19967, 35449, 325809, 593589, 5473435, 10159187, 93929982, 176846933
OFFSET
1,3
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Søren Eilers, Oct 29 2006
EXTENSIONS
More terms by Søren Eilers, Sep 12 2018
STATUS
approved