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a(n) is the degree of the polyomino with binary code A246521(n+1) in the n-omino graph defined in A098891.
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%I #23 Dec 07 2023 14:53:37

%S 0,0,1,1,4,3,4,3,2,10,9,5,9,10,9,8,9,10,9,4,2,16,28,16,14,12,12,18,15,

%T 20,21,16,16,16,15,18,20,11,14,13,18,6,12,16,18,11,9,11,15,22,20,11,

%U 19,14,16,3,38,36,35,33,31,32,38,25,31,38,17,14,30,14,26

%N a(n) is the degree of the polyomino with binary code A246521(n+1) in the n-omino graph defined in A098891.

%C Number of free polyominoes that can be made from the polyomino with binary code A246521(n+1) by moving one of its cells (not counting itself).

%C Can be read as an irregular triangle, whose m-th row contains A000105(m) terms, m >= 1.

%H Pontus von Brömssen, <a href="/A367126/b367126.txt">Table of n, a(n) for n = 1..6473</a> (rows 1..10).

%H <a href="/index/Pol#polyominoes">Index entries for sequences related to polyominoes</a>.

%F a(n) >= A367439(n).

%e As an irregular triangle:

%e 0;

%e 0;

%e 1, 1;

%e 4, 3, 4, 3, 2;

%e 10, 9, 5, 9, 10, 9, 8, 9, 10, 9, 4, 2;

%e ...

%e For n = 8, A246521(8+1) = 30 is the binary code of the S-tetromino. By moving one cell of the S-tetromino, we can obtain the L, O, and T tetrominoes (but not the I tetromino), so a(8) = 3.

%Y Cf. A000105, A098891, A246521, A367123, A367124 (row maxima), A367125, A367439, A367443.

%K nonn,tabf

%O 1,5

%A _Pontus von Brömssen_, Nov 05 2023