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A123808
Number of ways to build a contiguous building with n LEGO blocks of size 1 X 7 on top of a fixed block of the same size so that the building is flat, i.e., with all blocks in parallel position.
0
13, 190, 3289, 59970, 1154985, 22797643, 461266481, 9477047041
OFFSET
1,1
COMMENTS
The base block is not counted among the n and must be the only block in the bottom layer of the building.
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved