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Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed.
2

%I #19 Sep 09 2019 01:47:11

%S 1,4,18,76,315,1296,5320,21800,89190,364460,1487948,6070332,24750570,

%T 100868236,410919990,1673486992,6813529348,27734769756,112874034844,

%U 459295593200,1868653768443,7601716598916,30920563717052,125759730486432,511445050400275,2079809585544808,8457048866652588,34386482811155244

%N Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed.

%D Dan Hoey, Bill Gosper and Richard C. Schroeppel, Discussions in Math-Fun Mailing list, circa Jul 13 1999.

%H Jean-François Alcover, <a href="/A048664/b048664.txt">Table of n, a(n) for n = 1..56</a>

%H R. C. Schroeppel, <a href="http://www.experimentalmath.info/workshop2004/schroeppel-talk.pdf">A few mathematical experiments</a>, Experimental Mathematics Workshop, Oakland, 2004.

%F a(n) = n * A001168(n). - _Andrew Howroyd_, Dec 04 2018

%t A001168 = Cases[Import["https://oeis.org/A001168/b001168.txt", "Table"], {_, _}][[All, 2]];

%t a[n_] := n A001168[[n]];

%t Array[a, 56] (* _Jean-François Alcover_, Sep 08 2019, after _Andrew Howroyd_ *)

%Y Cf. A001168, A048663.

%Y A row of A094166.

%K nonn

%O 1,2

%A _Dan Hoey_

%E More terms from Richard C. Schroeppel, May 04 2004