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A123776 Number of ways to build a contiguous building with n LEGO blocks of size 1 X 3 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
5, 28, 185, 1287, 9456, 71167, 549076, 4300975, 34154107, 273998400, 2217436152, 18074303774, 148232462372 (list; graph; refs; listen; history; text; internal format)
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.
LINKS
CROSSREFS
Sequence in context: A179326 A156629 A331797 * A070779 A189487 A367049
KEYWORD
nonn,hard
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved

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Last modified March 19 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)