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A123825
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2x3 which is symmetric after a rotation by 180 degrees.
0
1, 1, 25, 53, 1189, 2947, 66094, 181955, 3979943
OFFSET
1,3
CROSSREFS
KEYWORD
nonn
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved