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A006770 Number of fixed n-celled polyominoes which need only touch at corners.
(Formerly M3565)
13
1, 4, 20, 110, 638, 3832, 23592, 147941, 940982, 6053180, 39299408, 257105146, 1692931066, 11208974860, 74570549714, 498174818986, 3340366308393 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Also known as fixed polyplets. - David Bevan, Jul 28 2009
REFERENCES
D. H. Redelmeier, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
S. Mertens, Lattice animals: a fast enumeration algorithm and new perimeter polynomials, J. Stat. Phys. 58 (5-6) (1990) 1095-1108, Table 1.
Eric Weisstein's World of Mathematics, Polyplet.
Wikipedia, Pseudo polyomino
EXAMPLE
a(2)=4: the two fixed dominoes and the two rotations of the polyplet consisting of two cells touching at a vertex. - David Bevan, Jul 28 2009
a(3)=20 counts 4 rotations (by 0°, 45°, 90°, 135°) of the straight ... trinomino, and 8 rotations (by multiples of 45°) of the L-shaped .: trinomino and the ..· 3-polyplet, cf. link to the image. - M. F. Hasler, Sep 30 2014
CROSSREFS
Cf. A030222 (free polyplets).
10th row of A366767.
Sequence in context: A262394 A271932 A153295 * A158827 A263854 A026156
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
One more term from Joseph Myers, Sep 26 2002
STATUS
approved

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Last modified April 23 22:36 EDT 2024. Contains 371917 sequences. (Running on oeis4.)