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A057425 Number of rotationally symmetric 2n-celled polyominoes with 1 hole. 0
1, 7, 42, 193, 853, 3553, 14564, 58636, 234523 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,2

LINKS

Table of n, a(n) for n=5..13.

Tomás Oliveira e Silva, Enumeration of polyominoes

CROSSREFS

Sequence in context: A110451 A212144 A266387 * A248329 A073376 A094429

Adjacent sequences:  A057422 A057423 A057424 * A057426 A057427 A057428

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Sep 05 2000

STATUS

approved

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Last modified December 15 04:23 EST 2019. Contains 329991 sequences. (Running on oeis4.)