id:A123765 - 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 1x2 which is flat, i.e. with all blocks in parallel position, and symmetric after a rotation by 180 degrees.

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1, 1, 3, 4, 12, 18, 52, 83, 235, 389, 1087, 1851, 5113, 8891, 24357, 43045, 117127, 209731, 567487, 1027245 (list; graph; listen)

	OFFSET	`1,3`
	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: A064140 A064139 A026744 this_sequence A124817 A124818 A124638` `Adjacent sequences: A123762 A123763 A123764 this_sequence A123766 A123767 A123768`
	KEYWORD	`nonn`
	AUTHOR	`Soren Eilers (eilers(AT)math.ku.dk), Oct 29 2006`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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