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 A006762 Number of strictly 2-dimensional fixed polyominoes with n cells. (Formerly M3534) 4
 0, 0, 4, 17, 61, 214, 758, 2723, 9908, 36444, 135266, 505859, 1903888, 7204872, 27394664, 104592935, 400795842, 1540820540, 5940738674, 22964779658, 88983512781, 345532572676, 1344372335522, 5239988770266, 20457802016009, 79992676367106, 313224032098242, 1228088671826971 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS This sequence counts only polyominoes that are strictly 2-dimensional - it excludes those where all the squares are in a single line. Thus for n > 1, a(n) = A001168(n) - 2. - Franklin T. Adams-Watters, Jul 29 2007 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS W. F. Lunnon, Counting multidimensional polyominoes, Computer Journal 18 (1975), no. 4, pp. 366-367. FORMULA a(n) = A001168(n) - 2 for n > 1. - Franklin T. Adams-Watters, Jul 29 2007 CROSSREFS A column of A195739. Cf. A001168. Sequence in context: A202974 A034331 A107278 * A297917 A202752 A286210 Adjacent sequences:  A006759 A006760 A006761 * A006763 A006764 A006765 KEYWORD nonn AUTHOR EXTENSIONS Name clarified and a(18)-a(28) from Andrew Howroyd, Dec 04 2018 STATUS approved

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Last modified August 19 18:33 EDT 2019. Contains 326133 sequences. (Running on oeis4.)