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A283108
Number of fixed polyominoes minus number of free polyominoes for order n.
1
0, 0, 1, 4, 14, 51, 181, 652, 2356, 8625, 31791, 118195, 442261, 1665299, 6302903, 23968090, 91513682, 350687935, 1348198490, 5198114444, 20094107710, 77860452105, 302340714990, 1176325327796, 4584989069865, 17900574971247, 69993587545033, 274071021159757, 1074577571232370
OFFSET
0,4
COMMENTS
a(n) is the number of fixed polyominoes that are a transform -- except through identity -- of a canonical polyomino.
E.g., n=3:
________|_________
| |
canon | transform
|
* |
* |
* | * * *
|
* | * * * * *
* * | * * * *
LINKS
FORMULA
a(n) = A001168(n) - A000105(n).
CROSSREFS
Sequence in context: A117421 A034743 A096241 * A211303 A247415 A292463
KEYWORD
nonn
AUTHOR
Francois Alcover, Feb 28 2017
STATUS
approved