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A123803
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x7 which is symmetric after a rotation by 180 degrees.
0
1, 2, 52, 617, 6052, 86534, 814679, 12560687
OFFSET
1,2
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved