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A123781
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Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.
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0
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1, 1, 5, 7, 41, 65, 384, 649, 3853, 6745, 40209, 72334, 431188, 791144, 4717533, 8787824, 52396271, 98784645
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OFFSET
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1,3
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LINKS
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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