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%I #57 Dec 21 2022 08:19:34
%S 1,4,35,1280,263374,205666062
%N Number of distinct free polyominoes that will fit in a square of size n X n.
%C A268416 gives the number of polyominoes that fill fit inside an n X n square, but with the restriction that they have their edges aligned with the sides of the square. The current sequence removes that restriction, and hence differs from A268416 at a(5). See link "Explanation of a(5)".
%H John Mason, <a href="/A268427/a268427_1.pdf">Explanation of a(5)</a>
%H Talmon Silver, <a href="/A268427/a268427_2.pdf">Computing a(6)</a>
%e For n = 2, the four polyominoes are the 1 X 1, 1 X 2, and 2 X 2 squares or rectangles, and the 3-celled L-shape. - _N. J. A. Sloane_, Jan 21 2021
%Y Cf. A000105 (free polyominoes), A268416, A339848.
%K nonn,more
%O 1,2
%A _John Mason_, Feb 04 2016
%E A value for a(6) was submitted by _Sam Vodovoz_ on Aug 02 2020 but this was retracted via email on Aug 03 2020. - _N. J. A. Sloane_, Aug 03 2020
%E a(5) corrected by _Talmon Silver_, Sep 24 2020
%E a(6) from _Talmon Silver_, Oct 01 2020
%E Added "free" to definition. - _N. J. A. Sloane_, Jan 21 2021