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 A210986 Number of fixed polyominoes with 2n cells. 6
 2, 19, 216, 2725, 36446, 505861, 7204874, 104592937, 1540820542, 22964779660, 345532572678, 5239988770268, 79992676367108, 1228088671826973, 18946775782611174, 293560133910477776, 4565553929115769162, 71242712815411950635 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Jean-François Alcover, Table of n, a(n) for n = 1..28 Eric Weisstein's World of Mathematics, Polyomino Wikipedia, Polyomino FORMULA a(n) = A001168(2*n). MATHEMATICA A001168 = Cases[Import["https://oeis.org/A001168/b001168.txt", "Table"], {_, _}][[All, 2]]; a[n_] := A001168[[2 n]]; a /@ Range[1, Length[A001168]/2 // Floor] (* Jean-François Alcover, Sep 22 2019 *) CROSSREFS Bisection of A001168. Cf. A210987, A210988, A210996, Sequence in context: A037071 A126039 A091852 * A232525 A024227 A106945 Adjacent sequences:  A210983 A210984 A210985 * A210987 A210988 A210989 KEYWORD nonn AUTHOR Omar E. Pol, Sep 16 2012 STATUS approved

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Last modified December 10 15:09 EST 2019. Contains 329896 sequences. (Running on oeis4.)