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A123771 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 3 which is symmetric after a rotation by 180 degrees. 0
1, 2, 12, 45, 264, 1128, 6991, 32202, 202856, 973242, 6204349 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
S. Eilers, The LEGO counting problem, Amer. Math. Monthly, 123 (May 2016), 415-426.
CROSSREFS
Sequence in context: A275132 A276294 A066258 * A046991 A188982 A061990
KEYWORD
nonn,more
AUTHOR
Søren Eilers, Oct 29 2006
STATUS
approved

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Last modified July 22 14:07 EDT 2024. Contains 374499 sequences. (Running on oeis4.)