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 A126742 Number of n-indecomposable polyominoes with at least 2n cells. 5
 0, 2, 13, 284, 13375, 660690, 51941832 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A polyomino is called n-indecomposable if it cannot be partitioned (along cell boundaries) into two or more polyominoes each with at least n cells. For full lists of drawings of these polyominoes for n <= 6, see the links in A125759. LINKS N. MacKinnon, Some thoughts on polyomino tilings, Math. Gaz., 74 (1990), 31-33. Simone Rinaldi and D. G. Rogers, Indecomposability: polyominoes and polyomino tilings, The Mathematical Gazette 92.524 (2008): 193-204. EXAMPLE The five 2-indecomposable polyominoes: ...................X. XX..XXX..XX..XXX..XXX ..........X...X....X. Only the last two have >= 4 cells, so a(2) = 2. CROSSREFS Row sums of A126743. Cf. A000105, A125759, A125761, A125709, A125753. Sequence in context: A086510 A326360 A123113 * A013051 A012955 A011808 Adjacent sequences:  A126739 A126740 A126741 * A126743 A126744 A126745 KEYWORD nonn,more AUTHOR David Applegate and N. J. A. Sloane, Feb 01 2007 EXTENSIONS a(4) and a(5) from Peter Pleasants, Feb 13 2007 a(6) and a(7) from David Applegate, Feb 16 2007 STATUS approved

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Last modified December 7 22:29 EST 2019. Contains 329850 sequences. (Running on oeis4.)