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A123788
Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 5 which is flat, i.e., with all blocks in parallel position.
0
1, 5, 53, 623, 8075, 108463, 1499542, 21128897, 302219695, 4373563505
OFFSET
1,2
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved