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 A319321 a(n) is the number of d+/d- diagonally convex polyplets (polyominoes which need only touch at corners) with n cells. 0
 1, 4, 20, 108, 600, 3368, 18968, 106906, 602532, 3395402, 19131460, 107788900, 607274848 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A polyplet is d+ [d-] diagonally convex if the intersection of its interior with any line of slope 1 [-1] through the centers of the cells is connected. LINKS Table of n, a(n) for n=1..13. Adam Gruber, Java program to count lattice animals. EXAMPLE The only tetraplets that are not d+ diagonally convex are two animals consisting of a horizontal domino and a vertical domino joined at a corner. So a(4) = A006770(4) - 2 = 108. CROSSREFS Cf. A006770 (fixed polyplets), A187077 (row convex polyplets), A187276 (d+/d- diagonally convex polyominoes). Sequence in context: A263965 A265084 A321111 * A321574 A225621 A375303 Adjacent sequences: A319318 A319319 A319320 * A319322 A319323 A319324 KEYWORD nonn,more AUTHOR David Bevan, Sep 27 2018 STATUS approved

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Last modified September 15 02:41 EDT 2024. Contains 375930 sequences. (Running on oeis4.)