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A130622 Number of polyominoes with perimeter at most 2n. 0
0, 1, 2, 5, 11, 36, 122, 538 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The perimeter of a polyomino is always even. a(n) is partial sums of A057730 - Number of polyominoes (A000105) with perimeter 2n. a(n+1) >= A130866(n) - Number of polyominoes (or square animals) with at most n cells.

I wonder if there's another prime value beyond {2, 5, 11}?

LINKS

Table of n, a(n) for n=0..7.

CROSSREFS

Cf. A131482: a(n) is the number of n-celled polyominoes with perimeter 2n+2.

Sequence in context: A101834 A117758 A284251 * A112600 A156014 A268397

Adjacent sequences:  A130619 A130620 A130621 * A130623 A130624 A130625

KEYWORD

hard,more,nonn

AUTHOR

Tanya Khovanova, Aug 10 2007

STATUS

approved

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Last modified August 21 17:33 EDT 2017. Contains 290891 sequences.