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A030228 Number of n-celled polyominoes without bilateral symmetry. 5
0, 0, 0, 2, 6, 25, 88, 335, 1215, 4534, 16823, 63159, 237679, 900341, 3423201, 13073163, 50095285, 192599091, 742576616, 2870584814, 11122879867, 43191525139, 168046317330, 654998425237, 2557224396342, 9999083912711, 39153000738695, 153511081627903 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

A000105(n) + a(n) = A000988(n) because the number of free polyominoes plus the number of polyominoes lacking bilateral symmetry equals the number of one-sided polyominoes. - Graeme McRae, Jan 05 2006

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..45

FORMULA

a(n) = A000988(n) - A000105(n). - Graeme McRae, Jan 05 2006

a(n) = A006749(n) + A006747(n) + A144553(n). - Andrew Howroyd, Dec 04 2018

CROSSREFS

Cf. A000105, A000988, A006747, A006749, A030227, A144553.

Sequence in context: A073545 A103063 A220191 * A066317 A027104 A019048

Adjacent sequences:  A030225 A030226 A030227 * A030229 A030230 A030231

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

Terms a(23) and beyond from Andrew Howroyd, Dec 04 2018

STATUS

approved

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Last modified January 18 16:40 EST 2019. Contains 319271 sequences. (Running on oeis4.)