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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 CROSSREFS Cf. A131482: a(n) is the number of n-celled polyominoes with perimeter 2n+2. Sequence in context: A117758 A284251 A295495 * 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 December 16 01:14 EST 2018. Contains 318158 sequences. (Running on oeis4.)