id:A123820 - 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 2 X 2 which is symmetric after a rotation by 90 degrees.

+0
1

1, 1, 1, 1, 3, 4, 5, 10, 26, 38, 51, 121, 324, 488, 673, 1808 (list; graph; listen)

	OFFSET	`1,5`
	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: A082612 A122413 A136366 this_sequence A133320 A128920 A006288` `Adjacent sequences: A123817 A123818 A123819 this_sequence A123821 A123822 A123823`
	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.

AT&T Labs Research