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A123787
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x5 which is symmetric after a rotation by 180 degrees.
0
1, 2, 28, 192, 1680, 13644, 118916, 1044873, 9160772
OFFSET
1,2
CROSSREFS
KEYWORD
nonn
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved