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A057730
Number of polyominoes (A000105) with perimeter 2n.
11
0, 1, 1, 3, 6, 25, 86, 416, 1988, 10640, 57987, 328956, 1900321, 11204350, 67042778, 406780346
OFFSET
1,4
COMMENTS
Does this include polyominoes with holes? - Franklin T. Adams-Watters, Sep 12 2006. Answer from R. J. Mathar: Yes! See the illustrations in the links (e.g. perimeter 16, area 7, No 81 or perimeter 16, area 8, No 174).
All lines (sides of cells which are not common to a pair of cells) contribute to the perimeter, including the interior sides of cavities and holes. - R. J. Mathar, Feb 19 2021
CROSSREFS
Cf. A000105, A002931, A057753, A266549 (same, but holes not allowed), column sums of A342243, A131487 (polyominoes by total number of edges).
Sequence in context: A148663 A361288 A266549 * A350752 A355967 A074432
KEYWORD
nonn,nice,more
AUTHOR
N. J. A. Sloane, Oct 29 2000
EXTENSIONS
Additional comments from Barry Cipra, Jun 08 2004
Link updated by William Rex Marshall, Dec 16 2009
a(9)-a(10) added by Luca Petrone, Jan 08 2016
a(1)-a(9) confirmed by Bert Dobbelaere, Oct 19 2018
a(10)-a(12) corrected and extended by John Mason, Jul 26 2021
a(13)-a(16) added by John Mason, Sep 08 2022
STATUS
approved