id:A123771 - OEIS Search Results

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Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1x3 which is symmetric after a rotation by 180 degrees.

+0
1

1, 2, 12, 45, 264, 1128, 6991, 32202, 202856, 973242, 6204349 (list; graph; listen)

	OFFSET	`1,2`
	REFERENCES	`M. Abrahamsen and S. Eilers, Efficient counting of LEGO buildings, in preparation` `B. Durhuus and S. Eilers, On the entropy of LEGO, arXiv:math.CO/0504039`
	LINKS	`S. Eilers, LEGO counts`
	CROSSREFS	`Sequence in context: A028570 A009074 A066258 this_sequence A046991 A061990 A006742` `Adjacent sequences: A123768 A123769 A123770 this_sequence A123772 A123773 A123774`
	KEYWORD	`nonn`
	AUTHOR	`Soren Eilers (eilers(AT)math.ku.dk), Oct 29 2006`

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.

AT&T Labs Research