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A194596 Number of free non-polyominoes. 0
0, 1, 3, 17, 82, 489, 2923, 18401, 116848, 753726, 4898579, 32085696, 211398614, 1400292492, 9318028028, 62259251309, 417496576187 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Non-polyominoes are figures (like polyominoes), but are orthogonally connected at least in one vertex. So this number is equal to number of (free) n-polyplets minus number of free polyominoes: a(n) = A030222(n) - A000105(n).

LINKS

Table of n, a(n) for n=1..17.

Eric W. Weisstein, MathWorld: Polyplet

EXAMPLE

XX...X.X..X.. (the 3 for n=3)

..X...X....X.

............X

a(3) = 5 - 2 = 3

a(4) = 22 - 5 = 17

a(5) = 94 - 12 = 82

CROSSREFS

Cf. A030222, A000105, A006770 (fixed polyplets), A001168 (fixed polyominoes).

Sequence in context: A164305 A202247 A225342 * A217623 A083217 A225307

Adjacent sequences:  A194593 A194594 A194595 * A194597 A194598 A194599

KEYWORD

nonn

AUTHOR

Jani Melik, Aug 30 2011

STATUS

approved

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Last modified May 25 04:50 EDT 2019. Contains 323539 sequences. (Running on oeis4.)